Linker Functionalization and pH Tuning Enhance Solar-Driven Catalytic CO2 Reduction in MOF-5
Abstract
The wide band gap of metal-organic framework (MOF) 5 constrains its use in photocatalytic carbon dioxide (CO2) reduction despite its high porosity and favorable mass-transport properties. Adopting a state-of-the-art first-principles approach, we systematically investigate the effects of volumetric strain, metal-node substitution, linker functionalization, and pH control as knobs to improve the CO2 photocatalytic ability of MOF-5. Strain and metal-node substitution negligibly affect the gap, whereas linker functionalization narrows it into the visible range via in-gap states while preserving reduction-side alignment at pH = 0. The resulting reduction energetics are strongly sensitive to both linker functionalization and pH. Halogenated and hydroxylated frameworks provide access primarily to HCOOH, CO, and HCHO under alkaline conditions, principally with the Mg and Zn nodes, whereas COOH functionalization offers the broadest thermodynamic accessibility across the full CO2 reduction sequence. NH2 retains thermodynamic feasibility for all target reduction pathways but with larger overpotentials, while NO2 generally yields unfavorable reduction energetics. Crucially, within the COOH series, the choice of the metal node tunes the fundamental gap by over 1 eV with only minor changes in the reduction overpotentials, placing Sr- and Ba-based architectures as the most favorable ones for broad product selectivity with visible-light excitation. Linker functionalization substantially reduces the spatial overlap of the frontier states, promoting photoinduced charge separation. Taken together, these results establish linker functionalization and solution pH as complementary design levers for independently tuning light absorption and CO2-reduction energetics in MOF-5, establishing a rational and viable route for designing efficient MOF-based photocatalysts.
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BibTeX
@misc{santanaandreo2026linker,
title = {{Linker Functionalization and pH Tuning Enhance Solar-Driven Catalytic CO$_2$ Reduction in MOF-5}},
author = {Julia Santana-Andreo and Joshua Edzards and Surender Kumar and Caterina Cocchi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.02256},
eprint = {2609.02256},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.02256},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Linker Functionalization and pH Tuning Enhance Solar-Driven Catalytic CO_2 Reduction in MOF-5
AU - Julia Santana-Andreo
AU - Joshua Edzards
AU - Surender Kumar
AU - Caterina Cocchi
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.02256
UR - https://arxiv.org/abs/2609.02256
AB - The wide band gap of metal-organic framework (MOF) 5 constrains its use in photocatalytic carbon dioxide (CO_2) reduction despite its high porosity and favorable mass-transport properties. Adopting a state-of-the-art first-principles approach, we systematically investigate the effects of volumetric strain, metal-node substitution, linker functionalization, and pH control as knobs to improve the CO_2 photocatalytic ability of MOF-5. Strain and metal-node substitution negligibly affect the gap, whereas linker functionalization narrows it into the visible range via in-gap states while preserving reduction-side alignment at pH = 0. The resulting reduction energetics are strongly sensitive to both linker functionalization and pH. Halogenated and hydroxylated frameworks provide access primarily to HCOOH, CO, and HCHO under alkaline conditions, principally with the Mg and Zn nodes, whereas COOH functionalization offers the broadest thermodynamic accessibility across the full CO_2 reduction sequence. NH_2 retains thermodynamic feasibility for all target reduction pathways but with larger overpotentials, while NO_2 generally yields unfavorable reduction energetics. Crucially, within the COOH series, the choice of the metal node tunes the fundamental gap by over 1 eV with only minor changes in the reduction overpotentials, placing Sr- and Ba-based architectures as the most favorable ones for broad product selectivity with visible-light excitation. Linker functionalization substantially reduces the spatial overlap of the frontier states, promoting photoinduced charge separation. Taken together, these results establish linker functionalization and solution pH as complementary design levers for independently tuning light absorption and CO_2-reduction energetics in MOF-5, establishing a rational and viable route for designing efficient MOF-based photocatalysts.
ER -