Ion-conductive metal-organic frameworks

7review sections

7material families

14review claims

22secondary benchmarks

26cited studies

6research gaps

Review scope

To summarise historical background, fundamental design principles and notable secondary benchmarks for MOFs that conduct protons, hydroxide ions, lithium ions, sodium ions and magnesium ions through ordered pores or channels.

Coverage: 1979–2020
Category: Review Energy Storage
Material scope: ion-conductive metal-organic frameworks · proton-conductive MOFs · hydroxide ion-conductive MOFs · Li+, Na+ and Mg2+ ion-conductive MOFs · MOFs with guest acids, salts, solvents or hydrogen-bonding media
Transport scope: ionic conductivity · Grotthuss and vehicle proton mechanisms · hydroxide proton-back-transfer · carrier concentration and mobility design · transference-number caveats for multicomponent salt/solvent systems

Application scope: fuel cells · alkaline fuel cells · solid-state electrolytes · secondary batteries · energy conversion and storage context
Explicit exclusions: electronic conduction in conductive MOFs · full primary synthesis recipes · exhaustive extraction of all ionic conductivity values · non-MOF solid electrolytes except as contextual comparators
Source: p001 · Abstract
Evidence role: Context, taxonomy and secondary benchmarking

Section map

The review’s argument is preserved as a navigable set of section summaries.

Conclusions

p011-p012

Concludes that proton and hydroxide MOFs have reached high conductivities, whereas Li+/Na+/Mg2+ systems remain lower and need deeper mechanistic investigation.

Relevance: Core · p012 · Conclusions

Hydroxide ion-conductive MOFs

p008-p009

Introduces hydroxide-ion mobility, proton back-transfer, base-stability constraints and type A/type B strategies for OH- incorporation.

Relevance: Core · p008 · Hydroxide ion-conductive MOFs

Introduction

p001-p002

Frames ionic conduction in solids, introduces MOFs as ordered porous solids, and defines two MOF design requirements: introduce an ionic carrier and build a suitable mobile-ion environment.

Relevance: Core · p001 · Introduction

Conduction of other ionic carriers in MOFs

p009-p011

Reviews Li+, Na+ and Mg2+ conductive MOFs, usually with salts and solvents in pores, while stressing ambiguity over carrier identity and bulk versus external liquid contributions.

Relevance: Core · p009 · Conduction of other ionic carriers in MOFs

Proton-conductive MOFs

p002-p003

Reviews why protons dominate the MOF ion-conduction literature, contrasts vehicle and Grotthuss mechanisms, and presents early and 2009-era historical examples.

Relevance: Core · p002 · Proton-conductive MOFs

Proton conduction in MOFs under anhydrous conditions

p007-p008

Explains the need for non-humidified proton conductors above 100 C and surveys imidazole, triazole and phosphate-based approaches.

Relevance: Core · p007 · 2.2. Proton conduction in MOFs under anhydrous conditions

Proton conduction in MOFs with H2O molecules

p003-p007

Covers hydrated proton-conductive MOFs where acids, ammonium/protic cations, water networks, functional groups, defects and grain boundaries modulate conductivity.

Relevance: Core · p003 · 2.1. Proton conduction in MOFs with H2O molecules

Taxonomies

Classification systems are attributed to this review and are not treated as a global material registry.

Mechanistic Suitability For MOF PoresAuthor-proposed

Carrier families by transport support

The review distinguishes proton/hydroxide systems with efficient hydrogen-bond-mediated motion from heavier cations whose conductivity often depends on included salts and solvents.

Categories: H+ and OH- with protic media and Grotthuss-like transfer · Li+, Na+ and Mg2+ with salts/solvents and transference caveats

p009 · Conduction of other ionic carriers in MOFs

MOF Design PrincipleAuthor-proposed

Two requirements for ion-conductive MOFs

High conductivity is framed as the product of carrier concentration and mobility, so MOF design must supply both carriers and pathways/media.

Categories: introduction of ionic carrier into pores · construction of suitable environment/pathway for mobile ions

p001 · Introduction

Charge Compensation For OH-, Li+, Na+ And Mg2+ In MOFsAuthor-proposed

Type A/type B introduction of non-proton carriers

Figure 16 extends charge-compensation logic beyond protons, including hydroxide and battery-relevant cations.

Categories: Type A: carrier as counter ion of charged framework · Type B: salt inclusion with counter ion

p008 · Hydroxide ion-conductive MOFs · Fig. 16

Charge Compensation And Proton-Source Location

Types I-III for acidic species in proton-conductive MOFs

Figure 3 classifies proton-carrier introduction by where acidic species sit relative to the framework and charge-balance requirement.

Categories: Type I: protic counter cations in anionic framework · Type II: acidic groups on the framework · Type III: charge-neutral acidic species in voids

p003 · 2.1. Proton conduction in MOFs with H2O molecules · Fig. 3

Proton Transport Mechanism

Vehicle versus Grotthuss proton conduction

The review uses activation energy and hydrogen-bonding networks to interpret whether proton transport is likely Grotthuss-dominated.

Categories: vehicle diffusion of protonated species · Grotthuss proton hopping through hydrogen bonds

p002-p003 · Proton-conductive MOFs

Solid-State Ion Transport Architecture

Structural types of good ionic conductors

The introduction places MOFs within a broader solid-electrolyte taxonomy where ion migration needs voids, averaged sites or defects.

Categories: layered or channel/porous structure · mean structure with averaged ion occupancy · defect structure with vacant neighbouring sites

p001 · Introduction

Material families

Review-defined families retain their representative materials and conduction descriptions.

Anhydrous proton-conductive MOFs with imidazole/triazole/phosphate media

1D Channels Or Layered Hydrogen-Bond Networks

MOFs where non-volatile proton-conducting molecules or phosphate networks replace water for operation above 100 C.

Conduction: Self-dissociation and molecular motion of imidazole/triazole/phosphate media dominate anhydrous proton transfer.

Representative materials: [Al(mu2-OH)(1,4-ndc)]n with imidazole · beta-PCMOF2(Tz)x · [Zn(H2PO4)2(TzH)2]n

Nodes / linkers: Al3+ · Na+ framework salt · Zn2+ · naphthalenedicarboxylate · benzenedicarboxylate · trihydroxy-benzenetrisulfonate · phosphate · triazole

p007-p008 · 2.2. Proton conduction in MOFs under anhydrous conditions

Li+, Na+ and Mg2+ salt/solvent-included MOFs

1D Channels Or 3D Porous Frameworks

MOFs incorporating battery-relevant cations, counter-anions and liquid/ether solvents in pores or channels.

Conduction: Conductivity depends on salt/solvent inclusion and possible anion trapping; transference number and guest location are central caveats.

Representative materials: Mg(dobdc) with LiBF4/LiOiPr · UiO-66 with LiOtBu/PC · Li[Cu2Cl3BTDD].10(PC) · MOF-688 with Li+ · Mg2(dobpdc) with Mg salts and triglyme

Nodes / linkers: Mg2+ · Zr4+ · Cu · polyoxometalate clusters · dobdc · dobpdc · BTDD · tetrakis(4-formylphenyl)methane

p010-p011 · Conduction of other ionic carriers in MOFs

Functionalised MIL-53 proton conductors

1D Channels In MIL-53 Framework

MIL-53-type [M(OH)(bdc-R)] frameworks where functional groups provide acidic sites in 1D channels.

Conduction: Humidity-assisted proton conduction follows functional-group acidity, with carboxylic acid giving the highest values in the reviewed series.

Representative materials: [M(OH)(bdc-COOH)] · [M(OH)(bdc-OH)] · [M(OH)(bdc-H)] · [M(OH)(bdc-NH2)]

Nodes / linkers: Al3+ · Fe3+ · 1,4-benzenedicarboxylate derivatives

p005 · 2.1. Proton conduction in MOFs with H2O molecules

Hydrated ammonium/adipic acid zinc oxalate MOFs

2D Layered/Honeycomb Framework

Anionic [Zn2(ox)3]2- frameworks containing ammonium ions, adipic acid and water in layered/honeycomb spaces.

Conduction: Hydrogen-bonding networks among COOH, NH4+ and H2O support proton conduction; replacing NH4+ weakens the network.

Representative materials: (NH4)2(adp)[Zn2(ox)3].3H2O · K2(adp)[Zn2(ox)3].3H2O · Rb2(adp)[Zn2(ox)3].3H2O

Nodes / linkers: Zn2+ · oxalate · adipic acid

p003-p004 · 2.1. Proton conduction in MOFs with H2O molecules

Hydroxide ion-conductive MOFs

3D Cages Or 1D Channels

Base-stable or cationic frameworks that include hydroxide ions with water or hydroxide salts in pores.

Conduction: OH- conduction is rationalised through water-assisted proton back-transfer, but base stability and aperture size can limit mobility.

Representative materials: (NBu4)m(A)n{Zn(mim)2}6 · [Cu6(NDI)3].[EVIm]OH · [Ni2(m-pymca)3]OH.nH2O

Nodes / linkers: Zn2+ · Cu · Ni · 2-methylimidazolate · naphthalene tetracarboxydiimide derivative · m-pymca

p008-p009 · Hydroxide ion-conductive MOFs

Mixed-valence oxalate 2D frameworks with protic cations

2D Framework

[MII MIII(ox)3]- honeycomb frameworks with protonated ammonium or carboxylated ammonium cations in the interlayer space.

Conduction: Proton conduction arises from protic cations and adsorbed water; hydrophilicity of the cation controls low-humidity performance.

Representative materials: {NH(prol)3}[MCr(ox)3].nH2O · {NMe3(CH2COOH)}[MCr(ox)3].nH2O

Nodes / linkers: Cr3+ · Mn2+ · Fe2+ · Co2+ · oxalate · protic ammonium cations

p005 · 2.1. Proton conduction in MOFs with H2O molecules

Acid-functionalised and defect-engineered UiO-66

3D Framework

Zr-based UiO-66 frameworks modified by sulfonic acid groups or ligand defects to provide framework-bound proton sources.

Conduction: Strong acidic substituents and Lewis-acidic defect sites enhance hydrated proton conduction, but stability and post-synthetic chemistry matter.

Representative materials: UiO-66(SO3H) · UiO-66(SH)2 · defect-engineered UiO-66

Nodes / linkers: Zr4+ clusters · benzene dicarboxylate derivatives · sulfonated linkers · defective linker sites

p005-p007 · 2.1. Proton conduction in MOFs with H2O molecules

Synthesis strategies

Review-level synthesis principles remain separate from primary-study recipes.

Introduce proton carriers by charge-compensated acidic species

Use anionic frameworks with protic counterions, framework-bound acidic groups, or neutral acidic guests in voids to provide proton sources while retaining conducting media.

Claimed effects: Creates rational proton-conducting pathways by colocating acid carriers and hydrogen-bonding media.

Controlling variables: framework charge · acid location · water content · acid strength

Representative materials: (NH4)2(adp)[Zn2(ox)3].3H2O · MIL-53-bdc-R

Caveat: Water content and hydrogen-bond topology strongly affect observed conductivity.

p003 · 2.1. Proton conduction in MOFs with H2O molecules

Use base-stable or cationic MOFs for hydroxide incorporation

Introduce OH- directly as a counterion in cationic frameworks or include hydroxide salts in robust neutral frameworks.

Claimed effects: Allows water-assisted hydroxide transport through proton-back-transfer-like pathways.

Controlling variables: framework base stability · counter-cation identity · water uptake · pore aperture

Representative materials: ZIF-8-based hydroxide MOF · [Cu6(NDI)3].[EVIm]OH · [Ni2(m-pymca)3]OH.nH2O

Caveat: MOFs are often unstable to strong base and small apertures can raise activation energy.

p008-p009 · Hydroxide ion-conductive MOFs

Defect engineering as a proton-source strategy

Create ligand defects in UiO-66 by varying solvents or modulators, producing Lewis-acidic sites that behave as proton sources under humidified conditions.

Claimed effects: Tunes proton conductivity without changing the apparent UiO-66 crystal structure.

Controlling variables: modulating ligand · solvent · defect concentration · humidity

Representative materials: defect-engineered UiO-66

Caveat: Defect concentration must be controlled and interpreted against possible water-mediated conduction.

p006-p007 · 2.1. Proton conduction in MOFs with H2O molecules

Introduce non-volatile proton-conducting media for anhydrous operation

Load imidazole or triazole into pores, or build phosphate/triazole hydrogen-bond networks, to avoid loss of water above 100 C.

Claimed effects: Enables proton conduction under non-humidified or anhydrous conditions relevant to simplified fuel-cell operation.

Controlling variables: guest loading · channel size · guest molecular motion · temperature

Representative materials: [Al(mu2-OH)(1,4-ndc)]n with imidazole · beta-PCMOF2(Tz)x · [Zn(H2PO4)2(TzH)2]n

Caveat: Higher guest loading is not automatically better; molecular mobility can control conductivity.

p007 · 2.2. Proton conduction in MOFs under anhydrous conditions

Post-synthetic installation of strong acid groups

Convert preinstalled thiol groups into sulfonic acid groups on acid-tolerant frameworks such as UiO-66.

Claimed effects: Greatly increases proton conductivity by raising framework acid strength in type II proton-conductive MOFs.

Controlling variables: framework acid tolerance · pre-functional linker · oxidation chemistry · humidity

Representative materials: UiO-66(SO3H)

Caveat: Strong acids/bases can destabilise many MOFs, so robust frameworks are required.

p005 · 2.1. Proton conduction in MOFs with H2O molecules

Include battery cation salts and solvating guests in MOF pores

Use open metal sites, charged frameworks or ion-exchangeable frameworks to introduce Li+, Na+ or Mg2+ with counter-anions and solvents.

Claimed effects: Creates MOF-based ion conductors for battery-relevant cations, often reaching about 10^-4 S cm^-1.

Controlling variables: salt identity · solvent identity · open metal sites · framework charge · transference number

Representative materials: Mg(dobdc) with Li salts · Li[Cu2Cl3BTDD].10(PC) · MOF-688 · Mg2(dobpdc) with Mg salts

Caveat: Carrier identity, anion contribution, liquid outside crystallites and guest location can remain unresolved.

p011 · Conduction of other ionic carriers in MOFs

Review claims

These are the review authors’ synthesis, not newly measured results.

Consensus SummaryHigh supportStructure Property Link

For type II proton-conductive MOFs, stronger acidic framework functional groups generally improve proton conduction.

Evidence basis: multi_reference

Caveat: Very strong acid installation is synthetically difficult because many MOFs are acid/base sensitive.

p005 · 2.1. Proton conduction in MOFs with H2O molecules

Author InterpretationHigh supportStructure Property Link

In the ammonium/adipate zinc oxalate system, NH4+ assists construction of the proton-conducting hydrogen-bond network; K+ and Rb+ analogues conduct much less.

Evidence basis: single_reference

Caveat: The review attributes the difference to hydrogen-bond-network changes, not framework topology changes.

p004 · 2.1. Proton conduction in MOFs with H2O molecules

Author InterpretationMedium supportApplication Relevance

Fuel-cell-relevant proton MOFs should operate under non-humidified conditions above 100 C to avoid humidifiers, cooling systems and excess catalyst.

Evidence basis: review_reasoning

Caveat: The statement is a design target rather than evidence of device readiness.

p007 · 2.2. Proton conduction in MOFs under anhydrous conditions

Author InterpretationMedium supportCaveat

MOF-based ion conductors face application constraints including water-vapour decomposition, fuel crossover in fuel cells and electrochemical stability in batteries.

Evidence basis: review_reasoning

Caveat: The review lists these as issues rather than resolving them quantitatively.

p011 · Conduction of other ionic carriers in MOFs

Author InterpretationHigh supportCaveat

For Li+/Na+/Mg2+ salt-included MOFs, observed conductivity may include anion conduction or liquid outside microcrystals, so transference numbers and guest-location evidence are needed.

Evidence basis: multi_reference

Caveat: This caveat is central before using salt-included MOFs as primary cation-conduction evidence.

p011 · Conduction of other ionic carriers in MOFs

Author InterpretationHigh supportStructure Property Link

Crystalline MOFs allow proton-conducting hydrogen-bond networks to be visualised by crystallography, making them useful platforms for pathway-structure studies.

Evidence basis: multi_reference

Caveat: Disordered guests or salt/solvent inclusion can still prevent full pathway determination.

p002 · Proton-conductive MOFs

Author InterpretationHigh supportStructure Property Link

The review interprets MOF conductivity through carrier concentration and mobility; framework structure influences both n and mu.

Evidence basis: review_reasoning

Caveat: The relation is a simplifying design equation, not a complete mechanistic model.

p001 · Introduction

Author InterpretationMedium supportMeasurement Interpretation

Grain-boundary or surface conduction can dominate proton conductivity in some MOF powders and may be hard to separate from bulk conduction in impedance spectra.

Evidence basis: multi_reference

Caveat: Single impedance components may obscure bulk versus interparticle pathways.

p006 · 2.1. Proton conduction in MOFs with H2O molecules

Consensus SummaryMedium supportTransport Mechanism

Grotthuss proton hopping is treated as more efficient than the vehicle mechanism and often inferred from low activation energies below roughly 0.4 eV.

Evidence basis: multi_reference

Caveat: The review presents the activation-energy criterion as empirical expectation rather than definitive proof.

p003 · Proton-conductive MOFs

Consensus SummaryMedium supportTransport Mechanism

Hydroxide ion mobility in MOFs is rationalised by accepting protons from neighbouring water molecules through hydrogen bonds, analogous to Grotthuss-type transfer.

Evidence basis: multi_reference

Caveat: Specific MOF examples can have high activation barriers if pores or apertures restrict motion.

p008 · Hydroxide ion-conductive MOFs

Author InterpretationMedium supportCaveat

Although hydroxide-conductive MOFs can reach high conductivity, their structure-property relationships are less deeply investigated than proton-conductive MOFs.

Evidence basis: review_reasoning

Caveat: The claim is comparative within the reviewed literature up to 2020.

p012 · Conclusions

Author InterpretationMedium supportTransport Mechanism

In imidazole-included anhydrous MOFs, molecular motion of the included imidazole can control proton conductivity more directly than loading amount alone.

Evidence basis: single_reference

Caveat: Based on comparison of two aluminium frameworks rather than a broad library.

p007 · 2.2. Proton conduction in MOFs under anhydrous conditions

Consensus SummaryHigh supportDefinition Scope

MOF porous and channel structures are fundamentally suitable as ion-conducting pathways because they can host ionic carriers and conducting media in ordered voids.

Evidence basis: multi_reference

Caveat: Suitability does not guarantee high conductivity without carrier introduction and mobility control.

p001 · Abstract

Consensus SummaryMedium supportMaterial Comparison

Li+, Na+ and Mg2+ conductive MOFs were reported less often and generally reach about 10^-4 S cm^-1, lower than proton or hydroxide examples.

Evidence basis: multi_reference

Caveat: Comparisons are secondary and measurement conditions vary across original studies.

p012 · Conclusions

Secondary benchmarks

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
Secondary[Al(mu2-OH)(1,4-ndc)]n with imidazole	proton conductivity	2.2 x 10^-5 S cm^-1	120 C, anhydrous imidazole-loaded Text · Exact Reported	No verified corpus mapping	p007 · 2.2. Proton conduction in MOFs under anhydrous conditions
Secondarybeta-PCMOF2(Tz)x	proton conductivity	5 x 10^-4 S cm^-1	150 C; triazole-included Text · Exact Reported	No verified corpus mapping	p008 · 2.2. Proton conduction in MOFs under anhydrous conditions
Secondarycopper dithiooxamide coordination polymer	proton conductivity	2.2 x 10^-6 S cm^-1	27 C, 100% RH Text · Exact Reported	No verified corpus mapping	p002 · Proton-conductive MOFs
Secondary[Cu6(NDI)3].[EVIm]OH	hydroxide ionic conductivity	5.7 x 10^-2 S cm^-1	30 C, 95% RH Text · Exact Reported	No verified corpus mapping	p009 · Hydroxide ion-conductive MOFs
Secondarydefect-engineered UiO-66 with 1.0 ligand defects per formula	proton conductivity	6.8 x 10^-3 S cm^-1	60 C, 95% RH Text · Exact Reported	No verified corpus mapping	p006-p007 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryK2(adp)[Zn2(ox)3].3H2O	proton conductivity	1.2 x 10^-4 S cm^-1	25 C, 98% RH Text · Exact Reported	No verified corpus mapping	p004 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryLa and Pr [Ln(H5L)(H2O)4] compounds	proton conductivity	>10^-3 S cm^-1	reviewed humidified conditions Text · Approximate	No verified corpus mapping	p006 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryMg2(dobpdc).0.46Mg(TFSI)2.0.21Mg(OPhCF3)2.4.8triglyme	magnesium ionic conductivity	2.5 x 10^-4 S cm^-1	reviewed ambient conditions with Mg salts and triglyme Text · Exact Reported	No verified corpus mapping	p011 · Conduction of other ionic carriers in MOFs
SecondaryMg(dobdc) with LiBF4 and LiOiPr	lithium ionic conductivity	3.1 x 10^-4 S cm^-1	30-70 C range; highest sample with both LiBF4 and LiOiPr Text · Exact Reported	No verified corpus mapping	p010 · Conduction of other ionic carriers in MOFs
SecondaryMIL-53-based [M(OH)(bdc-R)]	proton conductivity	10^-8-10^-5 S cm^-1	25-80 C, 95% RH Text · Range	No verified corpus mapping	p005 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryMOF-688 with Li+ and propylene carbonate	lithium ionic conductivity	3.4 x 10^-4 S cm^-1	20 C Text · Exact Reported	No verified corpus mapping	p010 · Conduction of other ionic carriers in MOFs
Secondary(NH4)2(adp)[Zn2(ox)3].nH2O anhydrate phase	proton conductivity	~10^-12 S cm^-1	dehydrated/0% RH Text · Approximate	research_0324	p004 · 2.1. Proton conduction in MOFs with H2O molecules
Secondary(NH4)2(adp)[Zn2(ox)3].nH2O dihydrate phase	proton conductivity	~10^-5-10^-4 S cm^-1	10-90% RH stable dihydrate range Text · Range	research_0324	p004 · 2.1. Proton conduction in MOFs with H2O molecules
Secondary(NH4)2(adp)[Zn2(ox)3].3H2O	proton conductivity	0.8 x 10^-2 S cm^-1	25 C, 98% RH Text · Exact Reported	research_0220	p003 · 2.1. Proton conduction in MOFs with H2O molecules
Secondary[Ni2(m-pymca)3]OH.nH2O	hydroxide ionic conductivity	0.8 x 10^-4 S cm^-1	27 C, 99% RH Text · Exact Reported	No verified corpus mapping	p009 · Hydroxide ion-conductive MOFs
Secondary[La(H5L)(H2O)4] / PCMOF-5	proton conductivity	1.3 x 10^-3 S cm^-1	21.5 C, 98% RH Text · Exact Reported	No verified corpus mapping	p006 · 2.1. Proton conduction in MOFs with H2O molecules
Secondary[Pt(dach)(bpy)Br]4(SO4)4.32H2O	proton conductivity	1.7 x 10^-2 S cm^-1	50 C, 95% RH Text · Exact Reported	No verified corpus mapping	p007 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryRb2(adp)[Zn2(ox)3].3H2O	proton conductivity	4.3 x 10^-5 S cm^-1	25 C, 98% RH Text · Exact Reported	No verified corpus mapping	p004 · 2.1. Proton conduction in MOFs with H2O molecules
Secondarysurface MOF	proton conductivity	around 3.9 x 10^-3 S cm^-1	room temperature Text · Approximate	No verified corpus mapping	p006 · 2.1. Proton conduction in MOFs with H2O molecules
SecondaryUiO-66(SO3H)	proton conductivity	8.4 x 10^-2 S cm^-1	80 C, 90% RH Text · Exact Reported	No verified corpus mapping	p005 · 2.1. Proton conduction in MOFs with H2O molecules
Secondary(NBu4)m(A)n{Zn(mim)2}6 hydroxide-included ZIF-8	hydroxide/protonic ionic conductivity	2.3 x 10^-8 S cm^-1	25 C, 99% RH Text · Exact Reported	research_0464	p008-p009 · Hydroxide ion-conductive MOFs
Secondary[Zn(H2PO4)2(TzH)2]n	proton conductivity	1.2 x 10^-4 S cm^-1	150 C, anhydrous Text · Exact Reported	No verified corpus mapping	p008 · 2.2. Proton conduction in MOFs under anhydrous conditions

Research gaps

Open questions are presented as review-author priorities, not conclusions from the primary database.

anhydrous proton conduction

High

Water-based proton conductors lose adsorbed water above 100 C; high conductivity under non-humidified >100 C conditions remains required.

Proposed direction: Introduce non-volatile conducting media such as imidazole or phosphoric acid into MOF pores.

p007 · 2.2. Proton conduction in MOFs under anhydrous conditions

bulk conductivity attribution

High

Liquid solvents or ionic liquids outside MOF microcrystals may contribute to measured conductivity, making bulk MOF transport ambiguous.

Proposed direction: Determine guest location, remove external liquid artefacts and separate bulk, surface and grain-boundary contributions.

p011 · Conduction of other ionic carriers in MOFs

application stability

Medium

Device use is constrained by humidified fuel-cell operation, water-vapour decomposition, fuel crossover and electrochemical stability of MOFs.

Proposed direction: Evaluate MOF conductors under realistic atmospheres and electrochemical windows before claiming device suitability.

p011 · Conduction of other ionic carriers in MOFs

hydroxide MOF mechanisms

Medium

The relationship between conductive properties and structure is less deeply investigated for hydroxide MOFs than for proton MOFs.

Proposed direction: Use crystallography, isotope effects and pathway analysis to connect OH- conductivity with pore water and framework structure.

p012 · Conclusions

Li/Na/Mg MOF literature depth

Medium

There are fewer MOF reports for Li+, Na+ and Mg2+ carriers, and their conductivity remains lower than proton/hydroxide systems.

Proposed direction: Develop better conducting pathways and carrier-specific designs for battery-relevant cations.

p012 · Conclusions

carrier identity in salt-included MOFs

High

For salt-included cation MOFs, it can be unclear whether conductivity comes from cations or anions.

Proposed direction: Measure transference numbers using appropriate non-blocking electrodes and distinguish cation from anion transport.

p011 · Conduction of other ionic carriers in MOFs

Cited-study map

Mappings show which printed review references have a verified counterpart in the frozen primary corpus.

Show 26 cited-study records

Reference	Study	Role and context	Corpus mapping
Ref. 161995	Title unavailable	mechanism_contextMechanistic reference for Grotthuss proton transport used by the review to contrast proton conduction with other ions.	Unmapped
Ref. 221979	Title unavailable	historical_development · transport_benchmarkOriginal early proton-conducting copper MOF/coordination-polymer example.	Unmapped
Ref. 242009	Title unavailable	taxonomy_source · transport_benchmarkProvides the Type I/III acidic-species design example and superprotonic hydrated MOF benchmark.	research_0220
Ref. 252009	Title unavailable	anhydrous_proton · transport_benchmarkAnhydrous imidazole-included MOF study used to link guest molecular motion and proton conductivity.	Unmapped
Ref. 262009	Title unavailable	anhydrous_proton · transport_benchmarkTriazole-included beta-PCMOF2 benchmark for proton conduction above 100 C and fuel-cell demonstration context.	Unmapped
Ref. 272014	Title unavailable	mechanism_contextReview source cited for the empirical activation-energy expectation for Grotthuss proton transport.	Unmapped
Ref. 282014	Title unavailable	structure_property · transport_benchmarkHydrate-phase comparison showing proton conductivity changes with crystalline hydrogen-bond networks.	research_0324
Ref. 292014	Title unavailable	structure_property · transport_benchmarkCounter-ion substitution study showing NH4+ hydrogen-bonding role in proton-conductive pathways.	Unmapped
Ref. 352011	Title unavailable	structure_property · transport_benchmarkFunctional-group series used to show acidity order controls proton conductivity in MIL-53-type MOFs.	Unmapped
Ref. 362015	Title unavailable	synthesis_strategy · transport_benchmarkPost-synthetic sulfonation example with very high humidified proton conductivity.	Unmapped
Ref. 372013	Title unavailable	transport_benchmark · mechanism_contextPhosphonic-acid MOF benchmark with low activation energy and acid/water hydrogen-bond network.	Unmapped
Ref. 382017	Title unavailable	measurement_caveat · transport_benchmarkLanthanide PCMOF-5 series used to discuss grain-size and grain-boundary contributions.	Unmapped
Ref. 392014	Title unavailable	measurement_caveatPowder versus single-crystal example used to show grain-boundary dominance.	Unmapped
Ref. 402013	Title unavailable	measurement_caveat · transport_benchmarkSurface MOF example used to argue surface/grain-boundary conduction can exceed bulk conduction.	Unmapped
Ref. 412015	Title unavailable	synthesis_strategy · transport_benchmarkDefect-engineered UiO-66 example where ligand defects tune proton conductivity.	Unmapped
Ref. 422020	Title unavailable	transport_benchmark · structure_propertyTubular Lewis-acidic MOF example with water-channel proton conduction.	Unmapped
Ref. 432012	Title unavailable	anhydrous_proton · transport_benchmarkAnhydrous phosphate/triazole MOF with anisotropic proton conduction.	Unmapped
Ref. 442002	Title unavailable	mechanism_contextTheoretical basis for hydroxide mobility via proton back-transfer.	Unmapped
Ref. 452014	Title unavailable	taxonomy_source · transport_benchmarkBasic hydroxide-introduction design and ZIF-8-based hydroxide benchmark.	research_0464
Ref. 472017	Title unavailable	hydroxide_benchmarkBase-stable neutral framework incorporating hydroxide salts, with high OH- conductivity.	Unmapped
Ref. 482016	Title unavailable	hydroxide_benchmark · mechanism_contextType A cationic hydroxide MOF with isotope evidence for proton back-transfer.	Unmapped
Ref. 492011	Title unavailable	battery_cation_benchmarkLithium-ion conduction in Mg(dobdc) with salts and carbonate solvents.	Unmapped
Ref. 502013	Title unavailable	battery_cation_benchmarkUiO-66 type B lithium salt/solvent example.	Unmapped
Ref. 512017	Title unavailable	battery_cation_benchmark · transference_contextBTDD framework examples for lithium, sodium and magnesium conductivity and cation transference discussion.	Unmapped
Ref. 522019	Title unavailable	battery_cation_benchmark · transference_contextType A lithium ion-conductive MOF with cation exchange and high Li+ transference number.	Unmapped
Ref. 532014	Title unavailable	battery_cation_benchmarkMagnesium-ion conduction in Mg MOFs with salts and triglyme.	Unmapped