Hydrogen‐Bond‐Network Breakdown Boosts Selective CO2 Photoreduction by Suppressing H2 Evolution

Conventional strategies for highly efficient and selective CO2 photoreduction focus on the design of catalysts and cocatalysts. In this study, we discover that hydrogen bond network breakdown in reaction system can suppress H2 evolution, thereby improving CO2 photoreduction performance. Photosensitive poly(ionic liquid)s are designed as photocatalysts owing to their strong hydrogen bonding with solvents. The hydrogen bond strength is tuned by solvent composition, thereby effectively regulating H2 evolution (from 0 to 12.6 mmol g−1 h−1). No H2 is detected after hydrogen bond network breakdown with trichloromethane or tetrachloromethane as additives. CO production rate and selectivity increase to 35.4 mmol g−1 h−1 and 98.9 % with trichloromethane, compared with 0.6 mmol g−1 h−1 and 26.2 %, respectively, without trichloromethane. Raman spectroscopy and theoretical calculations confirm that trichloromethane broke the systemic hydrogen bond network and subsequently suppressed H2 evolution. This hydrogen bond network breakdown strategy may be extended to other catalytic reactions involving H2 evolution. In this study, we discover that breaking down the hydrogen bond network can suppress the H2 evolution side reaction in CO2 photoreduction, leading to improved CO production. We design a series of photosensitive poly(ionic liquid)s as photocatalysts to study the effect of hydrogen bond network on CO2 photoreduction. The optimized CO rate and selectivity are 35.4 mmol g−1 h−1 and 98.9 %, respectively, with no H2 detected.