Shae Patel, Kim McKelvey, and Lujia Liu · Chemistry of Materials · 2024
Review MOF-based electrocatalysts for CO2 reduction by active-site generation and by performance-enhancement strategy, with emphasis on stability, charge transport, current density, selectivity and prospects versus state-of-the-art CO2 electrolysers.
The review’s argument is preserved as a navigable set of section summaries.
Reviews insulating metal-node or organic-linker active sites including HKUST-1, ZIFs, Bi-MOFs and In-BDC, stressing weak conductivity and poor stability verification.
Relevance: Core · p10058 · Evolution of MOF Electrocatalysts
Covers single metal atoms embedded in linkers, especially metalloporphyrin, Rebpy and nickel dithiolene systems, with improved selectivity but remaining long-range charge-transfer limits.
Relevance: Core · p10065 · Second Generation: Single Atom Sites for CO2 Electrolysis · Table 4
Analyses conductive MOFs with active sites on nodes and/or linkers; MPc, catecholate, triptycene and related motifs improve electronic transport and enable higher-value products.
Relevance: Core · p10066 · Third Generation: Conductive Sites for CO2 Electrolysis
Treats ionic liquids, metal-electrode supports and GDEs as extrinsic routes to overcome ion conductivity and mass-transport limits.
Relevance: Core · p10073 · Boosting Performance via Experimental Configuration · Table 8
Reviews conductive polymers, metallocenes and fullerene/carbon guests inside MOF pores as added charge-transfer pathways.
Relevance: Core · p10074 · Enhancing Charge Transfer via Host-Guest Interactions
Frames CO2 electroreduction metrics, H-cell versus GDE operation, MOF advantages, intrinsic conductivity limits, and the need for post-electrolysis stability evidence.
Relevance: Core · p10056 · Introduction · Figure 2
Compares generational synthesis practicality and summarises limitations: conductivity, post-characterisation and need for enhancement strategies.
Relevance: Core · p10070 · Scalability and Summary of MOF Structural Evolution
Covers functionalisation, ligand/node doping, light-assisted electrocatalysis, state-of-the-art comparisons, mixed-valence prospects and final synthesis of the review argument.
Relevance: Core · p10080 · Summary
Classification systems are attributed to this review and are not treated as a global material registry.
The review's central organising scheme classifies MOF CO2 electrocatalysts by active-site structure rather than by product, metal or linker alone.
Categories: Generation 1: insulating metal node or linker active site · Generation 2: single metal atom embedded onto organic linker · Generation 3: conductive MOF with active site on any component
p10056 · Introduction · Figure 2
The review treats cell configuration as a major determinant of observed current density and scalability.
Categories: H-cell with dissolved CO2 · flow cell or gas diffusion electrode · liquid-phase GDE assembly · gas-phase GDE assembly
p10072 · Gas Diffusion Electrodes · Figure 12
Third-generation MOFs are interpreted through electronic coupling pathways that can reduce band gaps and increase current density.
Categories: through-bond orbital overlap · extended conjugation · through-space pi-pi interactions · redox hopping in mixed-valence nodes
p10066 · Third Generation: Conductive Sites for CO2 Electrolysis
The review separates intrinsic active-site evolution from extrinsic or local-environment enhancements that boost current density, FE or stability.
Categories: experimental configuration · host-guest interactions · secondary sphere interactions and doping · photo-assisted methods
p10058 · Introduction
Figure 9 distinguishes high-value products from lower electron-transfer products when comparing generations.
Categories: low electron-transfer products: CO and HCOOH · high-value products: CH4, C2H4, methanol, ethanol, acetate
p10069 · Third Generation: Conductive Sites for CO2 Electrolysis · Figure 9
Tables 3, 5 and 7 classify whether the original MOF remains the catalyst or may be a precatalyst/MOF-derived species.
Categories: structural profile verified · chemical profile verified · partial verification · no verification
p10058 · Introduction
Review-defined families retain their representative materials and conduction descriptions.
Copper-based azolate frameworks deployed in gas diffusion environments for high current density and hydrocarbon/C2+ production.
Conduction: Performance is coupled to GDE mass transport and copper active-site environments rather than only intrinsic bulk conductivity.
Representative materials: Cu-BTP · Cutrz · Cu-BTZ · Cu-DBC · NNU-33(H)
Nodes / linkers: Cu · azolate · triazolate · benzotriazolate
p10078 · State-of-the-Art Electrocatalysts and Outlook
Second-generation MOFs embedding single nickel bis(dithiolene) sites in a linker to mimic formate-dehydrogenase activity.
Conduction: Still low absolute conductivity, but local charge transfer around the Ni site improves performance relative to the analogue.
Representative materials: In(III)-(bdtdb(Ni)) · In(III)-TTFTB analogue
Nodes / linkers: In · Ni · bis(dithiolene)-dibenzoic acid · tetrathiafulvalene-tetrabenzoate
p10066 · Second Generation · Table 5
MOFs where traditional metal nodes or organic linkers act as CO2RR active sites despite being electrically insulating framework components.
Conduction: Generally poor electrical conductivity limits charge transfer and current density.
Representative materials: HKUST-1 · CR-MOF · Bi-BTC · In-BDC · CAU-17
Nodes / linkers: Cu · Bi · In · Zn · carboxylates · rubeanate · imidazolate
p10058 · First Generation: Metal Node and Organic Linker Sites for CO2 Electrolysis
MOF-545(Co) and related porphyrin MOFs implanted with conductive or redox-active guest species.
Conduction: Guest species provide additional electron-transfer pathways and can interact with active sites.
Representative materials: Ppy@MOF-545(Co) · CoCp2@MOF-545(Co) · C60@MOF-545(Co)
Nodes / linkers: Zr · Co · metalloporphyrin · conductive polymer guests · metallocene guests · fullerene guests
p10075 · Host-Guest Interactions · Table 9
Prospective MOFs with alternating oxidation states in metal nodes enabling redox-hopping charge transport.
Conduction: Reported charge transfer can reach around 10^1 S/cm, above typical conductive MOFs discussed in the review.
Representative materials: 3D tetrahydroxyquinone-based mixed-valence MOF · CuIICuI-organic frameworks
Nodes / linkers: Fe · Cu · tetrahydroxyquinone · redox-active organic frameworks
p10079 · Future Directions
Third-generation conductive MOFs using MPc linkers with amine, sulfide or catecholate terminals to improve orbital overlap and charge transport.
Conduction: Through-bond, extended conjugation and through-space pathways raise conductivity from typical 10^-10 S/cm MOFs toward 10^-5 to 10^-2 S/cm.
Representative materials: PcCo-Cu-O/C · PcCu-Cu-O · NiPc-Ni-NH · NiPc-NiO4 · MOF-1992/C
Nodes / linkers: Cu · Ni · Fe · Co · metallophthalocyanines · catecholates · amine terminals
p10067 · Third Generation · Figure 8
Second-generation MOFs using metalated TCPP or related porphyrin linkers as isolated active sites.
Conduction: High active-site density but carboxylate-linked frameworks often remain long-range charge-transfer limited.
Representative materials: MOF-525(Fe) · Al2(OH)2TCPP-Co · PCN-222(Fe)/C · Zn-TCPP(Co) · MOF-545(Co)-NH2
Nodes / linkers: Zr · Al · Zn · TCPP metalloporphyrins
p10063 · Second Generation · Figure 6
MOFs where groups outside the first coordination sphere or doped nodes/ligands tune intermediate binding, proton/electron transfer or hydrophobicity.
Conduction: Performance is attributed to local binding and transfer effects rather than solely bulk conductivity.
Representative materials: MOF-545(Co)-NH2 · UiO-66/TCPP-Fe · Zn-FJU-127-CH3 · Sn-MOF/In
Nodes / linkers: Zr · Fe · Zn · Sn · In · amino-functionalised porphyrins · methylated linkers · ligand-doped frameworks · node-doped frameworks
p10077 · Secondary Sphere Interactions and Doping
Zeolitic imidazolate frameworks where imidazolate ligands and/or metal nodes are implicated in CO2RR.
Conduction: Imidazolate-based linkers yield poor conductivity but N-coordinated environments can improve selectivity.
Representative materials: ZIF-8SO4 · ZIF-8 · 2D Ni(Im)2
Nodes / linkers: Zn · Ni · imidazolate
p10061 · First Generation
Review-level synthesis principles remain separate from primary-study recipes.
Select whether the active site is an insulating framework component, a single atom embedded in a linker, or part of an electrically conductive framework.
Claimed effects: Provides a structure-centred way to rationalise performance and stability trends.
Controlling variables: active-site location · linker coordination environment · metal node identity · bulk conductivity
Representative materials: HKUST-1 · In(III)-(bdtdb(Ni)) · NiPc-Ni-NH
Caveat: Generation boundaries simplify diverse chemistries and do not by themselves prove true active species.
p10057 · Introduction
Choose metal-node/linker pairs whose coordination bonds and redox potentials tolerate aqueous pH, applied potentials and local pH shifts.
Claimed effects: Improves confidence that the MOF remains the catalyst rather than becoming a MOF-derived species.
Controlling variables: metal valency · HSAB pairing · linker pKa · redox innocence · electrochemical double layer
Representative materials: In-BDC · In(III)-(bdtdb(Ni)) · Cu-BTP
Caveat: Chronoamperometry alone is not adequate; structural and chemical post-characterisation is required.
p10058 · Introduction
Introduce MPc, catecholate, amine or related conjugated linkers to create through-bond, extended-conjugation and through-space electronic pathways.
Claimed effects: Raises electrical conductivity and supports higher current density while retaining defined active sites.
Controlling variables: terminal donor atoms · metal-linker orbital overlap · 2D stacking · conjugation length
Representative materials: PcCo-Cu-O/C · NiPc-Ni-NH · MOF-1992/C
Caveat: Many examples still need longer stability testing and chemical-profile verification.
p10069 · Third Generation
Deliver gaseous CO2 directly to porous electrodes to overcome dissolved-CO2 mass-transport limits in H-cells.
Claimed effects: Can move MOF CO2RR from tens of mA/cm2 toward or above industrial current-density ranges.
Controlling variables: porous carbon support · hydrophobic PTFE layer · microporous layer · liquid-phase versus gas-phase assembly · electrolyte flow
Representative materials: Cu-BTP · Cutrz · Cu-BTZ · HKUST-1/GDE
Caveat: Some high-current GDE studies lack enough post-electrolysis characterisation to confirm stability.
p10072 · Gas Diffusion Electrodes · Figure 12
Use MOF porosity to locate conductive polymers, metallocenes or fullerene guests near active sites and create extra charge-transfer channels.
Claimed effects: Improves FE, partial current density and conductivity in several MOF-545(Co) systems.
Controlling variables: guest size · pore size · guest redox potential · polymer doping state · host-guest proximity
Representative materials: Ppy@MOF-545(Co) · CoCp2@MOF-545(Co) · C60@MOF-545(Co)
Caveat: Optimisation requires care because guest size and redox state can make the guest poorly positioned or less conductive under CO2RR potentials.
p10075 · Host-Guest Interactions
Employ ionic liquid electrolytes and metal electrode supports to improve CO2 solubility, local interactions and electron transfer.
Claimed effects: Can enhance selectivity and current density, especially for methane or formate formation in selected systems.
Controlling variables: ionic liquid cation/anion · CO2 solubility · metal support identity · electrode-MOF contact
Representative materials: Zn-BTC/IL · MFM-300(In)/In
Caveat: The review notes limited follow-up research and uncertain MOF stability in ionic-liquid environments.
p10071 · Ionic Liquid Electrolytes
Couple light-harvesting porphyrin units with electrochemical bias to stabilise intermediates and improve selected CO2RR rates or products.
Claimed effects: Light can improve partial current density, FE or high-value product formation in a small number of MOF examples.
Controlling variables: photoactive porphyrin metal · layer number · illumination · active-site rearrangement
Representative materials: PCN-222(Co) · copper-porphyrin monolayer MOF · MOF-545(Co)
Caveat: Only three examples were discussed and light-harvesting units beyond porphyrins remain mostly unexplored.
p10078 · Photo-Assisted Methods
Add functional groups, ligand dopants or node dopants outside the first coordination sphere to tune CO2/intermediate binding and proton/electron transfer.
Claimed effects: Can improve CO2RR over HER and steer product selectivity through local environment effects.
Controlling variables: NH2 or CH3 proximity · hydrophobic groups · ligand dopants · node dopants · hydrogen-bond donors
Representative materials: MOF-545(Co)-NH2 · UiO-66/TCPP-Fe · Zn-FJU-127-CH3 · Sn-MOF/In
Caveat: The influence of functionalities and doping is still not fully understood and needs broader materials coverage.
p10077 · Secondary Sphere Interactions and Doping
These are the review authors’ synthesis, not newly measured results.
The review's main interpretive contribution is to classify MOF CO2 electrocatalysts by active-site structure into first, second and third generations.
Evidence basis: review_reasoning
Caveat: This is the review authors' organising framework, not a universal field standard.
p10057 · Introduction
Crystal defects and missing components can degrade long-range charge transport but may expose active sites and sometimes improve catalytic performance.
Evidence basis: multi_reference
Caveat: The review summarises a tradeoff rather than giving a predictive rule.
p10057 · Introduction
First-generation MOFs established the field but many examples lack sufficient post-electrolysis structural and chemical data to confirm whether the MOF is the true electrocatalyst.
Evidence basis: multi_reference
Caveat: In-BDC is highlighted as a stronger stability example than most first-generation cases.
p10061 · First Generation · Table 3
GDE configurations are the most important reviewed experimental enhancement for reaching industrially relevant current density in MOF CO2RR.
Evidence basis: multi_reference
Caveat: High current does not automatically imply long-term durability or confirmed MOF stability.
p10073 · Experimental Configuration Enhancements · Table 8
H-cells using dissolved CO2 impose a mass-transport ceiling around 30 mA/cm2, motivating GDE and flow-cell configurations.
Evidence basis: multi_reference
Caveat: The value is a review-level heuristic for CO2-saturated aqueous solution.
p10056 · Introduction · Figure 1
High-value hydrocarbons and alcohols are mainly associated with third-generation copper single-atom environments such as Cu-O4 and Cu-N4.
Evidence basis: multi_reference
Caveat: Product assignment depends on configuration and stability; not all third-generation MOFs produce high-value products.
p10070 · Third Generation
Host-guest strategies use pore-confined conductive or redox-active guests to add electron-transfer pathways and improve local charge transfer in otherwise resistive MOFs.
Evidence basis: multi_reference
Caveat: Performance depends on guest redox state, pore fit and chemical stability.
p10075 · Host-Guest Interactions
Low electrical conductivity in many MOFs originates from poor orbital overlap between metal nodes and organic linkers, producing large band gaps and charge-transfer limitations.
Evidence basis: multi_reference
Caveat: Defects can either hinder long-range transport or expose active sites, so the link is not one-directional.
p10057 · Introduction
Mixed-valence MOFs could represent a future generation because redox-hopping pathways may provide much higher conductivity, but their water, pH and electrochemical stability for CO2RR remain unresolved.
Evidence basis: single_reference
Caveat: This is a future direction, not demonstrated CO2RR consensus.
p10079 · Future Directions
The review deliberately focuses on MOF-based catalysts with defined active sites rather than MOF-derived pyrolysis products, whose active sites are less structurally controllable.
Evidence basis: multi_reference
Caveat: MOF-derived materials remain relevant background but are outside the main extraction scope.
p10057 · Introduction
MOFs are attractive CO2RR electrocatalyst platforms because high surface area, porosity, modularity and tunability can disperse and tailor active sites.
Evidence basis: multi_reference
Caveat: These advantages must be balanced against low conductivity and stability concerns.
p10054 · Abstract
Photo-assisted MOF CO2RR shows improved performance in a few porphyrin examples, but the evidence base is small and light-harvesting units beyond porphyrins remain underexplored.
Evidence basis: multi_reference
Caveat: The review identifies only three examples to date.
p10078 · Photo-Assisted Methods
First-generation MOFs appear synthetically simpler and more scalable, whereas second- and third-generation designs often perform better but are more complex to produce at scale.
Evidence basis: review_reasoning
Caveat: The review calls for techno-economic and scalable-synthesis analysis rather than claiming commercial readiness.
p10078 · State-of-the-Art Electrocatalysts and Outlook
Second-generation MOFs improve selectivity through embedded single-atom sites but still suffer from poor long-range charge transfer and generally low partial current density.
Evidence basis: multi_reference
Caveat: The improvement is modest when averaged across the review tables.
p10065 · Second Generation · Table 4
Secondary-sphere functionalisation can stabilise CO2 intermediates, promote proton/electron transfer or suppress HER by changing the local active-site environment.
Evidence basis: multi_reference
Caveat: The review says the local dynamics remain partly unclear.
p10077 · Secondary Sphere Interactions and Doping
Chronoamperometry alone is not adequate stability evidence; structural and chemical profiles before and after electrolysis are needed to identify the true catalyst.
Evidence basis: multi_reference
Caveat: The review repeatedly marks studies as partial/no stability where such evidence is absent.
p10058 · Introduction
State-of-the-art CO2 electrocatalysts operate at 200-500 mA/cm2 with FE above 80%; only selected MOF/GDE systems approach or exceed this performance window.
Evidence basis: multi_reference
Caveat: Industrial lifetime targets are much longer than most MOF tests.
p10078 · State-of-the-Art Electrocatalysts and Outlook
Third-generation conductive MOFs generally show superior selectivity and current density compared with earlier generations because conductive frameworks combine better charge transport with defined active sites.
Evidence basis: multi_reference
Caveat: Most examples are still H-cell scale and remain below the best GDE current densities.
p10069 · Third Generation · Figure 9
ZIF-8 active-site assignment is not fully settled: one study supports imidazolate ligands with innocent Zn nodes, whereas the initial study suggested a reversible Zn redox wave.
Evidence basis: multi_reference
Caveat: The review presents this as an evidence tension requiring careful interpretation.
p10061 · First Generation
Every row remains visibly secondary and links to a primary dossier only where the mapping is verified.
| Material | Property | Reported value | Context and quality | Primary evidence | Review source |
|---|---|---|---|---|---|
| Secondary2D-vc-MOF(Cu) | partial current density and FE | 4.5 mA/cm2; FE 65% for CH4 at -1.4 V vs SHE | 0.1 M KCl; vertically extended triptycene MOF Table · Exact Reported | research_0740 | p10068 · Third Generation · Table 6 |
| SecondaryCoCp2@MOF-545(Co) | partial current density and FE | 25.6 mA/cm2; FE 85% for CO at -0.9 V vs SHE | 0.5 M KHCO3; metallocene host-guest enhancement Table · Exact Reported | No verified corpus mapping | p10075 · Host-Guest Enhancements · Table 9 |
| SecondaryCu-BTP | partial current density and FE | 1025 mA/cm2; FE 82% for CH4 + C2H4 at -1.6 V vs SHE; stability Yes (60 h) | 1 M KOH; third-generation MOF in GDE Table · Exact Reported | No verified corpus mapping | p10073 · Experimental Configuration Enhancements · Table 8 |
| SecondaryCu-BTZ | partial current density and FE | 581.6 mA/cm2; FE 62% for C2H4 + EtOH + AcOH at -1.6 V vs SHE; stability Yes (70 h) | 1 M KOH; third-generation MOF in GDE Table · Exact Reported | No verified corpus mapping | p10073 · Experimental Configuration Enhancements · Table 8 |
| SecondaryCu-DBC | partial current density and FE | 162.4 mA/cm2; FE 80% for CH4 at -0.9 V vs SHE; stability Yes (3 h) | 1 M KOH; third-generation MOF in GDE Table · Exact Reported | research_0757 | p10073 · Experimental Configuration Enhancements · Table 8 |
| SecondaryCutrz | partial current density and FE | 350 mA/cm2; FE 70% for C2H4 + EtOH + AcOH at -0.8 V vs SHE; stability Yes (80 h) | 1 M KHCO3; third-generation MOF in GDE Table · Exact Reported | No verified corpus mapping | p10073 · Experimental Configuration Enhancements · Table 8 |
| SecondaryCO2-saturated H-cell | current density limit | around 30 mA/cm2 | CO2 dissolved in aqueous solution; solubility ~34 mmol/L Text · Approximate | No verified corpus mapping | p10056 · Introduction · Figure 1 |
| SecondaryHKUST-1 | partial current density and FE | 9.8 mA/cm2; FE 51% for (COOH)2 at -2.3 V vs SHE | 0.01 M TBATFB/DMF; first-generation MOF Table · Exact Reported | No verified corpus mapping | p10061 · First Generation · Table 2 |
| SecondaryIn-BDC | partial current density, FE and stability evidence | 6.5 mA/cm2; FE 88% for HCOOH at -0.7 V vs SHE; 20 h stability with structural and chemical verification | 0.5 M KHCO3; first-generation MOF Table · Exact Reported | No verified corpus mapping | p10062 · First Generation · Tables 2-3; Figure 5 |
| SecondaryIn(III)-(bdtdb(Ni)) | electrical conductivity | 3.97 x 10^-8 S/cm | compared with In(III)-TTFTB analogue Text · Exact Reported | No verified corpus mapping | p10065 · Second Generation |
| SecondaryIn(III)-(bdtdb(Ni)) | partial current density and FE | 36 mA/cm2; FE 90% for HCOOH at -1.3 V vs SHE | 0.5 M KHCO3; second-generation single Ni site Table · Exact Reported | No verified corpus mapping | p10065 · Second Generation · Table 4 |
| SecondaryMFM-300(In)/In | partial current density and FE | 45.5 mA/cm2; FE 99% for HCOOH at -2 V vs SHE | 0.5 M EmimBF4/MeCN; ionic liquid plus support Table · Exact Reported | No verified corpus mapping | p10073 · Experimental Configuration Enhancements · Table 8 |
| Secondarymixed-valency MOFs | electrical conductivity future benchmark | ~10^1 S/cm compared to conductive MOFs ~10^-2 S/cm | mixed-valence redox hopping; future direction, not CO2RR benchmark Text · Approximate | research_0066 | p10079 · Future Directions |
| SecondaryMOF-1992/C | partial current density and FE | 13.2 mA/cm2; FE 80% for CO at -0.63 V vs SHE | 0.1 M KHCO3; 3D conductive MPc-catecholate MOF with carbon Table · Exact Reported | No verified corpus mapping | p10068 · Third Generation · Table 6 |
| SecondaryMOF-545(Co)-NH2 | partial current density and FE | 56 mA/cm2; FE 93% for CO at -1.24 V vs SHE | 0.1 M TBAPF6, 0.1 M H2O, 1 M TFE/DMF; secondary-sphere functionalisation Table · Exact Reported | No verified corpus mapping | p10077 · Secondary Sphere Enhancement · Table 10 |
| SecondaryNiPc-Ni-NH | partial current density and FE | 24.8 mA/cm2; FE 80% for CO at -1.1 V vs SHE | 0.5 M KHCO3; third-generation conductive MPc MOF Table · Exact Reported | No verified corpus mapping | p10068 · Third Generation · Table 6 |
| SecondaryPcCo-Cu-O/C | partial current density and FE | 14.7 mA/cm2; FE 85% for CO at -0.74 V vs SHE | 0.2 M KHCO3; third-generation conductive MPc MOF with carbon Table · Exact Reported | No verified corpus mapping | p10068 · Third Generation · Table 6 |
| SecondaryPcCu-Cu-O | partial current density and FE | 3.7 mA/cm2; FE 50% for C2H4 at -1.2 V vs SHE | 0.1 M KHCO3; third-generation copper MPc MOF Table · Exact Reported | No verified corpus mapping | p10068 · Third Generation · Table 6 |
| SecondaryPCN-222(Co) | photo-assisted partial current density | CO partial current density increased from 15 to 17 mA/cm2 at -1.1 V vs SHE under light | visible-light photo-assisted electroreduction; compared with dark Text · Exact Reported | No verified corpus mapping | p10078 · Photo-Assisted Methods · Figure 15 |
| SecondaryPpy@MOF-545(Co) | partial current density and FE | 11 mA/cm2; FE 98% for CO at -0.8 V vs SHE | 0.1 M KHCO3; host-guest conductive polymer Table · Exact Reported | No verified corpus mapping | p10075 · Host-Guest Enhancements · Table 9 |
| SecondaryRe-SURMOF | partial current density and FE | 2.3 mA/cm2; FE 93% for CO at -1.6 V vs SHE | 0.1 M TBAH/acetonitrile; second-generation MOF thin film Table · Exact Reported | No verified corpus mapping | p10065 · Second Generation · Table 4 |
| Secondarystate-of-the-art CO2 electrocatalysts | current density and FE performance window | 200-500 mA/cm2 with FE above 80% | state-of-the-art CO2 electrocatalysts, typically GDE cells Text · Range | No verified corpus mapping | p10078 · State-of-the-Art Electrocatalysts and Outlook |
| SecondaryUiO-66/TCPP-Fe | partial current density and FE | 3 mA/cm2; FE 99% for CO at -0.81 V vs SHE | 0.1 M KHCO3; ligand-doped/proton-transmitting UiO-66 support Table · Exact Reported | No verified corpus mapping | p10077 · Secondary Sphere Enhancement · Table 10 |
| SecondaryZIF-8 | partial current density and FE | 6.9 mA/cm2; FE 81% for CO at -1.1 V vs SHE | 0.25 M K2SO4; first-generation MOF Table · Exact Reported | No verified corpus mapping | p10061 · First Generation · Table 2 |
Open questions are presented as review-author priorities, not conclusions from the primary database.
Bulk conductivity remains a major limitation for first- and second-generation MOFs even when local active-site selectivity is high.
Proposed direction: Develop conductive linkers, redox hopping frameworks and host-guest charge-transfer pathways without sacrificing active-site definition.
p10066 · Second Generation
GDEs can deliver high current densities, but many GDE-enhanced MOF studies still have partial or absent stability evidence.
Proposed direction: Pair GDE performance testing with rigorous post-characterisation and stability protocols under realistic flow-cell conditions.
p10073 · Experimental Configuration Enhancements
Host-guest enhancement has mainly been demonstrated in a narrow range of MOF hosts and guest species.
Proposed direction: Explore broader MOF hosts, conductive guests and redox potentials, with pore-size matching and guest-state characterisation.
p10075 · Host-Guest Interactions
MOF tests are usually far shorter than industrial lifetime requirements and rarely use accelerated durability protocols.
Proposed direction: Subject promising MOFs to long-term electrolysis and ADT conditions approaching industrially relevant stress and duration.
p10078 · State-of-the-Art Electrocatalysts and Outlook
Mixed-valence MOFs offer high conductivity but their aqueous, pH and electrochemical stability for CO2RR remain uncertain.
Proposed direction: Separate redox-hopping metal nodes from CO2RR active sites and test water, pH and electrochemical stability under CO2RR conditions.
p10079 · Future Directions
Light-assisted MOF CO2RR is promising but represented by only a few porphyrin examples.
Proposed direction: Test non-porphyrin light-harvesting units such as metallophthalocyanines and benchmark light/dark controls consistently.
p10078 · Photo-Assisted Methods
Many MOF CO2RR studies lack sufficient post-electrolysis structural and chemical characterisation to identify the true catalyst.
Proposed direction: Routinely combine PXRD/SEM/TEM with spectroscopy such as XPS, XAS, Raman, FTIR or UV-vis before and after electrolysis.
p10058 · Introduction
Higher-performing second- and third-generation MOFs often involve more complex synthesis than first-generation materials.
Proposed direction: Assess green, scalable synthesis and techno-economic constraints alongside performance.
p10078 · State-of-the-Art Electrocatalysts and Outlook
The effects of functional groups, ligand doping and node doping on secondary-sphere interactions are not yet fully understood.
Proposed direction: Systematically vary local hydrogen-bond donors, hydrophobic groups and dopants using comparable active sites and conditions.
p10077 · Secondary Sphere Interactions and Doping
Mappings show which printed review references have a verified counterpart in the frozen primary corpus.
| Reference | Study | Role and context | Corpus mapping |
|---|---|---|---|
| Ref. 182021 | An industrial perspective on catalysts for low-temperature CO2 electrolysis | state_of_art_contextCited for industrially relevant current density, FE and durability context. | Unmapped |
| Ref. 252020 | Review-Electrochemical CO2 Reduction for CO Production: Comparison of Low- and High-Temperature Electrolysis Technologies | mass_transport_contextSupports the review's H-cell dissolved-CO2 mass-transport limit. | Unmapped |
| Ref. 352023 | Tailoring ligand fields of metal-azolate frameworks for highly selective electroreduction of CO2 to hydrocarbons at industrial current density | gde_benchmark · state_of_art_contextHighest-performing GDE MOF example highlighted in the review. | Unmapped |
| Ref. 542020 | Electrically Conductive Metal-Organic Frameworks | conductivity_context · transport_mechanismCore background for MOF conductivity limitations and conductive-framework design. | Unmapped |
| Ref. 902012 | Highly selective electrochemical reduction of carbon dioxide using Cu based metal organic framework as an electrocatalyst | first_generation_benchmark · historical_framingPioneering first-generation HKUST-1 CO2RR study. | Unmapped |
| Ref. 1102018 | Carbon dioxide electroreduction over imidazolate ligands coordinated with Zn(II) center in ZIFs | first_generation_benchmark · active_site_assignmentSupports ZIF-8 performance and imidazolate active-site interpretation. | Unmapped |
| Ref. 1152020 | Indium-Based Metal-Organic Framework for High-Performance Electroreduction of CO2 to Formate | first_generation_benchmark · stability_benchmarkFirst-generation MOF singled out as confidently stable with post-electrolysis characterisation. | Unmapped |
| Ref. 1262015 | Fe-Porphyrin-Based Metal-Organic Framework Films as High-Surface Concentration, Heterogeneous Catalysts for Electrochemical Reduction of CO2 | second_generation_benchmarkEarly second-generation porphyrin MOF benchmark. | Unmapped |
| Ref. 1302016 | Highly oriented MOF thin film-based electrocatalytic device for the reduction of CO2 to CO exhibiting high faradaic efficiency | second_generation_benchmark · thin_film_contextRe-bipyridine linker thin-film MOF benchmark with high FE but degradation caveat. | Unmapped |
| Ref. 1352021 | In(III) Metal-Organic Framework Incorporated with Enzyme-Mimicking Nickel Bis(dithiolene) Ligand for Highly Selective CO2 Electroreduction | second_generation_benchmark · stability_benchmarkKey second-generation formate benchmark and stability exemplar. | Unmapped |
| Ref. 1462020 | Hierarchical Tuning of the Performance of Electrochemical Carbon Dioxide Reduction Using Conductive Two-Dimensional Metallophthalocyanine Based Metal-Organic Frameworks | third_generation_benchmark · conductive_mofConductive 2D metallophthalocyanine MOF benchmark. | Unmapped |
| Ref. 1472021 | Highly Selective CO2 Electroreduction to C2H4 Using a Metal-Organic Framework with Dual Active Sites | third_generation_benchmark · high_value_productCopper MPc MOF example for ethylene production and dual active sites. | Unmapped |
| Ref. 1482021 | Conductive phthalocyanine-based metal-organic framework as a highly efficient electrocatalyst for carbon dioxide reduction reaction | third_generation_benchmark · conductive_mofConductive NiPc-Ni-NH framework benchmark. | Unmapped |
| Ref. 1492019 | Three-Dimensional Phthalocyanine Metal-Catecholates for High Electrochemical Carbon Dioxide Reduction | third_generation_benchmark · conductive_mof3D conductive MPc-catecholate MOF benchmark. | Unmapped |
| Ref. 1502023 | A Triptycene-Based 2D MOF with Vertically Extended Structure for Improving the Electrocatalytic Performance of CO2 to Methane | third_generation_benchmark · high_value_productVertically conductive triptycene MOF methane benchmark. | research_0740 |
| Ref. 1742016 | Highly efficient electrochemical reduction of CO2 to CH4 in an ionic liquid using a metal-organic framework cathode | experimental_configuration · ionic_liquidEarly ionic-liquid MOF enhancement example. | Unmapped |
| Ref. 1772020 | Quantitative Electro-Reduction of CO2 to Liquid Fuel over Electro-Synthesized Metal-Organic Frameworks | experimental_configuration · ionic_liquid_supportIonic-liquid plus metal-support enhancement benchmark. | Unmapped |
| Ref. 1842017 | Copper-Based Metal-Organic Porous Materials for CO2 Electrocatalytic Reduction to Alcohols | experimental_configuration · gdeInitial GDE implementation of HKUST-1 discussed in the review. | Unmapped |
| Ref. 1862022 | A Stable and Low-Cost Metal-Azolate Framework with Cyclic Tricopper Active Sites for Highly Selective CO2 Electroreduction to C2+ Products | gde_benchmark · high_value_productStable GDE C2+ benchmark in Table 8. | Unmapped |
| Ref. 1872022 | A Porous pi-pi Stacking Framework with Dicopper(I) Sites and Adjacent Proton Relays for Electroreduction of CO2 to C2+ Products | gde_benchmark · high_value_productHigh-current Cu-BTZ GDE C2+ benchmark. | Unmapped |
| Ref. 1882021 | Coordination environment dependent selectivity of single-site-Cu enriched crystalline porous catalysts in CO2 reduction to CH4 | gde_benchmark · high_value_productGDE methane benchmark. | research_0757 |
| Ref. 2002021 | Implanting Polypyrrole in Metal-Porphyrin MOFs: Enhanced Electrocatalytic Performance for CO2RR | host_guest · conductive_polymerConductive-polymer host-guest enhancement benchmark. | Unmapped |
| Ref. 2042020 | Metallocene implanted metalloporphyrin organic framework for highly selective CO2 electroreduction | host_guest · redox_mediatorMetallocene host-guest charge-transfer benchmark. | Unmapped |
| Ref. 2082023 | Local Weak Hydrogen Bonds Significantly Enhance CO2 Electroreduction Performances of a Metal-Organic Framework | secondary_sphere · benchmarkAmino-functionalised secondary-sphere benchmark. | Unmapped |
| Ref. 2192019 | Accelerated proton transmission in metal-organic frameworks for the efficient reduction of CO2 in aqueous solutions | secondary_sphere · ligand_dopingLigand-doped/proton-transmission secondary-sphere example. | Unmapped |
| Ref. 2252021 | Enhancing CO2 Electrocatalysis on 2D Porphyrin-Based Metal-Organic Framework Nanosheets Coupled with Visible-Light | photo_assisted · benchmarkEarliest photo-assisted MOF CO2RR example discussed. | Unmapped |
| Ref. 2272022 | Tailoring Layer Number of 2D Porphyrin-Based MOFs Towards Photocoupled Electroreduction of CO2 | photo_assisted · high_value_productPhoto-coupled Cu-porphyrin MOF example for layer-number effects and C2 products. | Unmapped |
| Ref. 2482020 | Valence-Dependent Electrical Conductivity in a 3D Tetrahydroxyquinone-Based Metal-Organic Framework | future_direction · conductivity_contextUsed for mixed-valence redox-hopping conductivity outlook. | research_0066 |