Synthesis · Highly Selective CO2 Electroreduction to CH4 by In Situ Generated Cu2O Single-Type Sites on a Conductive MOF: Stabilizing Key Intermediates with Hydrogen Bonding

9 structured synthesis routes

Completeness describes how fully the route could be reconstructed from the main article and supporting information.

Partial recipeSource: SI

Route 1: Electrochemical

p015 / SI p14 · Supporting Figures and Tables · Figure S18

Metal precursorsCuHHTP electrode

Linker precursorsHHTP in CuHHTP framework

Solvents0.1 M KCl/0.1 M KHCO3 electrolyte (by analogy to Cu2O@CuHHTP preparation)

AdditivesNafion binder from electrode ink

Atmospherenot specified

Temperatureroom temperature (implied)

Time1

Substrate orientationglassy carbon electrode

Oxidant / reductantelectrochemical reduction at -1.2 V vs RHE

Work-upnot specified

Activationnone beyond electroreduction

Scalability contextVariant of target electroreduction route with longer treatment time.

Show 2 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	CuHHTP electrode	not restated	p015 / SI p14 · Supporting Figures and Tables · Figure S18
Electrolyte	KCl/KHCO3	not restated; likely 0.1 M/0.1 M	p015 / SI p14 · Supporting Figures and Tables · Figure S18

Partial recipeSource: SI

Route 2: Electrochemical

p015 / SI p14 · Supporting Figures and Tables · Figure S19

Metal precursorsCuHHTP electrode

Linker precursorsHHTP in CuHHTP framework

Solvents0.1 M KCl/0.1 M KHCO3 electrolyte (by analogy to Cu2O@CuHHTP preparation)

AdditivesNafion binder from electrode ink

Atmospherenot specified

Temperatureroom temperature (implied)

Time3

Substrate orientationglassy carbon electrode

Oxidant / reductantelectrochemical reduction at -1.2 V vs RHE

Work-upnot specified

Activationnone beyond electroreduction

Scalability contextVariant of target electroreduction route with longer treatment time.

Show 2 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	CuHHTP electrode	not restated	p015 / SI p14 · Supporting Figures and Tables · Figure S19
Electrolyte	KCl/KHCO3	not restated; likely 0.1 M/0.1 M	p015 / SI p14 · Supporting Figures and Tables · Figure S19

Partial recipeSource: SI

Route 3: Electrochemical

p015 / SI p14 · Supporting Figures and Tables · Figure S20

Metal precursorsCuHHTP electrode

Linker precursorsHHTP in CuHHTP framework

Solvents0.1 M KCl/0.1 M KHCO3 electrolyte (by analogy to Cu2O@CuHHTP preparation)

AdditivesNafion binder from electrode ink

Atmospherenot specified

Temperatureroom temperature (implied)

Time5

Substrate orientationglassy carbon electrode

Oxidant / reductantelectrochemical reduction at -1.2 V vs RHE

Work-upnot specified

Activationnone beyond electroreduction

Scalability contextVariant of target electroreduction route with longer treatment time.

Show 2 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	CuHHTP electrode	not restated	p015 / SI p14 · Supporting Figures and Tables · Figure S20
Electrolyte	KCl/KHCO3	not restated; likely 0.1 M/0.1 M	p015 / SI p14 · Supporting Figures and Tables · Figure S20

Complete recipeSource: SI

Route 4: Drop Cast

p005 / SI p4 · Preparation of commercial Cu2O electrode

Metal precursorscommercial Cu2O, 5 mg

Solventsisopropanol, 1 mL

Additives2.5 mg conductive carbon black; 40 uL 5 wt% Nafion

Atmosphereambient; not specified

Temperatureroom temperature drying

Time0.5 h sonication; drying time not specified

Substrate orientationglassy carbon electrode with 10 mm GC disk

Oxidant / reductantnone

Work-up10 uL ink dropped on GCE and dried at room temperature

Activationnone reported

Scalability contextCommercial powder electrode fabrication only.

Show 4 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	commercial Cu2O	5 mg	p005 / SI p4 · Preparation of commercial Cu2O electrode
Additive	conductive carbon black (ketjen black)	2.5 mg	p005 / SI p4 · Preparation of commercial Cu2O electrode
Additive	Nafion	40 uL · 5 wt%	p005 / SI p4 · Preparation of commercial Cu2O electrode
Solvent	isopropanol	1 mL	p005 / SI p4 · Preparation of commercial Cu2O electrode

Complete recipeSource: SI

Route 5: Other

p003 / SI p2 · Preparation of Cu2O@conductive carbon black

Metal precursors100 uL of 0.1 M CuSO4 solution

Solvents9 mL deionized water; ethanol/water wash

Additives10 mg conductive carbon black (ketjen black); 350 uL 1.0 M NaOH

Atmospherenot specified

Temperature35

Time0.033 h crystal growth after ascorbic acid addition; water bath during process

Substrate orientationconductive carbon black support; later drop-cast on GCE for CO2RR

Oxidant / reductant500 uL of 0.2 M L-(+)-ascorbic acid reductant

Work-upcentrifuge at 8500 rpm for 10 min; decant; wash three times with 40 mL 1:1 water/ethanol

Activationnone reported

Scalability contextSmall vial synthesis in water bath.

Show 5 structured reagent records

Role	Reagent	Amount / concentration	Source
Metal Source	CuSO4 solution	100 uL · 0.1 M	p003 / SI p2 · Preparation of Cu2O@conductive carbon black
Base	NaOH solution	350 uL · 1.0 M	p003 / SI p2 · Preparation of Cu2O@conductive carbon black
Reductant	L-(+)-ascorbic acid	500 uL · 0.2 M	p003 / SI p2 · Preparation of Cu2O@conductive carbon black
Additive	conductive carbon black (ketjen black)	10 mg	p003 / SI p2 · Preparation of Cu2O@conductive carbon black
Solvent	deionized water	9 mL	p003 / SI p2 · Preparation of Cu2O@conductive carbon black

Complete recipeSource: Both

Route 6: Electrochemical

p003 / SI p2 · Preparation of Cu2O@CuHHTP

Metal precursorsCuHHTP electrode

Linker precursorsHHTP in CuHHTP framework

Solventsaqueous 0.1 M KCl/0.1 M KHCO3 electrolyte

AdditivesNafion binder from electrode ink

Atmospherenot specified for electroreduction preparation; CO2RR measurements later use CO2-saturated electrolyte

Temperatureroom temperature (implied)

Time0.5

Substrate orientationglassy carbon electrode

Oxidant / reductantelectrochemical reduction at -1.2 V vs RHE; Ag/AgCl reference; Pt foil counter electrode

Work-upused directly for CO2RR measurements and other characterisations

Activationnone beyond electrochemical reduction

Scalability contextElectrode-scale in situ generation, not bulk powder synthesis.

Show 3 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	CuHHTP electrode	from 10 uL ink	p003 / SI p2 · Preparation of Cu2O@CuHHTP
Electrolyte	KCl	0.1 M	p003 / SI p2 · Preparation of Cu2O@CuHHTP
Electrolyte	KHCO3	0.1 M	p003 / SI p2 · Preparation of Cu2O@CuHHTP

Vague recipeSource: Main

Route 7: Other

p005 / 23645 · Results and Discussion · Figure S14

Metal precursorscommercial Cu2O

Linker precursorsHHTP

Solventsnot reported

Additivesnot reported

Atmospherenot reported

Substrate orientationCO2RR electrode; details not stated

Oxidant / reductantnone stated

Work-upnot reported

Activationnone reported

Show 2 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	commercial Cu2O	not reported	p005 / 23645 · Results and Discussion · Figure S14
Linker	HHTP	not reported	p005 / 23645 · Results and Discussion · Figure S14

Complete recipeSource: SI

Route 8: Drop Cast

p003 / SI p2 · Preparation of Cu2O@CuHHTP

Metal precursorsCuHHTP powder, 5 mg

Solventsisopropanol, 1 mL

Additives40 uL 5 wt% Nafion

Atmosphereambient; not specified

Temperatureroom temperature drying

Time0.5 h ultrasonication; drying time not specified

Substrate orientationglassy carbon electrode with 10 mm GC disk

Oxidant / reductantnone

Work-up10 uL ink dropped on GCE and dried at room temperature

Activationnone reported

Scalability contextSmall drop-cast electrode preparation.

Show 3 structured reagent records

Role	Reagent	Amount / concentration	Source
Other	CuHHTP	5 mg	p003 / SI p2 · Preparation of Cu2O@CuHHTP
Additive	Nafion	40 uL · 5 wt%	p003 / SI p2 · Preparation of Cu2O@CuHHTP
Solvent	isopropanol	1 mL	p003 / SI p2 · Preparation of Cu2O@CuHHTP

Complete recipeSource: Both

Route 9: Solvothermal

p002-p003 / SI pp1-2 · Synthesis of CuHHTP

Metal precursorsCopper acetate (Cu(OAc)2.H2O), 128 mg in 40 mL methanol

Linker precursorsHHTP, 104 mg in 50 mL methanol

Solventsmethanol

Additivesnone reported

Atmospheresealed glass bottles; atmosphere not specified

Temperature65

Time24

Oxidant / reductantnone reported

Work-upcool naturally to room temperature; collect by centrifugation; wash with methanol three times

Activationdry at 70 deg C for 24 h in a vacuum oven

Scalability contextSolution transferred to nine 20 mL sealed glass bottles.

Show 3 structured reagent records

Role	Reagent	Amount / concentration	Source
Metal Source	Copper acetate (Cu(OAc)2.H2O)	128 mg · in 40 mL methanol	p002-p003 / SI pp1-2 · Synthesis of CuHHTP
Linker	HHTP	104 mg · in 50 mL methanol	p002-p003 / SI pp1-2 · Synthesis of CuHHTP
Solvent	methanol	90 mL total	p002-p003 / SI pp1-2 · Synthesis of CuHHTP