A Zero-Gap Gas Phase Photoelectrolyzer for CO2 Reduction with Porous Carbon Supported Photocathodes

With their variable active sites Metal–organic frameworks (MOFs) can achieve visible-light absorption and efficient charge separation for photocatalytic, and conductivity for electrocatalytic  CO₂   reduction into value added chemicals. This work illustrates the importance of porous carbon fiber layers (CFLs) on the activity and selectivity of MOF based  photocathodes towards the CO₂ reduction reaction (CO₂RR) in a zero-gap gas phase photoelectrolyzer. The wettability of the CFL modulates the local environment on the metal organic framework catalyst (UiO-66-NH₂, yellow coloured). Hydrophobic CFL-based MOF photocathodes lead to CO₂RR, producing liquid hydrocarbons ( CxHyOz) such as formate, methanol and ethanol. In contrast, hydrophilic, wetted CFL-based photocathodes favor the Hydrogen Evolution Reaction (HER).The results are a step further in understanding how the design and composition of the photoelectrodes in photoelectrochemical electrolyzers can impact the  CO₂  reduction efficiency and selectivity.