Artificial photosynthesis with metal and covalent organic frameworks (MOFs and COFs): challenges and prospects in fuel‐forming electrocatalysis

Abstract

Mimicking photosynthesis in generating chemical fuels from sunlight is a promising strategy to alleviate society's demand for fossil fuels. However, this approach involves a number of challenges that must be overcome before this concept can emerge as a viable solution to society's energy demand. Particularly in artificial photosynthesis, the catalytic chemistry that converts energy in the form of electricity into carbon‐based fuels and chemicals has yet to be developed. Here, we describe the foundational work and future prospects of an emerging and promising class of materials: metal‐ and covalent‐organic frameworks (MOFs and COFs). Within this context, these porous and tuneable framework materials have achieved initial success in converting abundant feedstocks (H2O and CO2) into chemicals and fuels. In this review, we first highlight key achievements in this direction. We then follow with a perspective on precisely how MOFs and COFs can perform in ways not possible with conventional molecular or heterogeneous catalysts. We conclude with a view on how spectroscopically probing MOF and COF catalysis can be used to elucidate reaction mechanisms and material dynamics throughout the course of reaction.

Synergistic electroreduction of carbon dioxide to carbon monoxide on bimetallic layered conjugated metal-organic frameworks

“…However, the CO 2 -to-CO conversion, involving the transfer of two electrons and two protons, typically suffers from high kinetic barriers and low selectivity due to the high thermodynamic/kinetic stability of CO 2 and the competing hydrogen evolution reaction (HER) in aqueous media, respectively 7,8 . Recently, great efforts have been dedicated to explore numerous electrocatalysts for catalytic CO 2 RR to CO, including noble metals (Au, Pd, Ag), transitionalmetal-based materials (Fe, Co, Ni, Cu, Zn) and heteroatom-doped porous carbons 2,7,[9][10][11][12][13][14][15][16][17] . Nevertheless, these single site catalysts still fail to meet the requirement of electrochemical syngas synthesis with tunable H 2 /CO ratio (from 1:1 to 3:1 or higher) at relatively low overpotential.…”

Molecular and heterogeneous water oxidation catalysts: recent progress and joint perspectives

“…383 Molecular species are either directly incorporated into the nano-voids of these porous materials or used as building blocks for the formation of novel frameworks. [384][385][386] These strategies are based on the assumption that the nanoscale confinement effect disables the intermolecular deactivation routes of molecular WOCs. Therefore, many of these systems offer the benefit of investigating molecular reaction pathways, while circumventing the issue of aggregationinduced destabilization.…”

Rational incorporation of defects within metal–organic frameworks generates highly active electrocatalytic sites

“…The utilization of metal and covalent organic frameworks (MOFs and COFs) in electrochemical systems is increasingly attracting interest because of the unique capabilities of these structures. [1][2][3][4][5] Through judicious selection of the organic linker and metal nodes, the porosity, internal chemistry, conductivity, active site physical and electronic structure can all be chosen a priori to generate the ideal catalyst. This degree of control is unmatched by conventional heterogeneous and molecular materials, thus opening up unique parameter spaces to explore.…”