Mechanism insights for efficient photocatalytic reforming of formic acid with tunable selectivity: Accelerated charges separation and spatially separated active sites

Photocatalytic reforming of formic acid (FA) is considered a promising energy conversion method for producing solar fuels and valuable chemical feedstocks to achieve the carbon-neutral goal. However, the application of FA photocatalytic reforming has been restricted by the low efficiency and relatively fixed selectivity due to limited knowledge about the reaction mechanism. Herein, we study the efficient CdS/W₂N₃ photocatalyst system for photoreforming of FA with tunable selectivity to realize the conversion of products from H₂ to syngas under simulated sunlight. Widely tunable CO:H₂ ratios between 0 and 2.18 along with a record-high apparent quantum yield (AQY) of 61.00% (H₂) and 76.84% (syngas) at 420 nm have been demonstrated. Both theoretical investigation and experimental results show that intrinsic N vacancies and spatially separated active sites are vital factors in achieving tunable selectivity. This work provides a insightful information to construct and understand the photocatalytic system for efficiently reforming of FA with tunable selectivity.