A Hybrid Photocatalytic System Splits Atmospheric Water to Produce Hydrogen

Abstract Large‐scale photocatalytic water‐splitting panel reactor system is developed and demonstrated its commercial feasibility. However, water scarcity is one of the leading challenges for the sustainable development of photocatalytic hydrogen generation in a well‐lit area. Here, a water harvesting form air‐photothermal water evaporation‐photocatalytic hydrogen evolution (AWPH) system is devised. The hybrid system comprising carbonized wood (CWx) combined with the hygroscopic salt ZnCl₂ and Pt‐modified g‐C₃N₄ nanosheets (Pt‐CN) as a photocatalyst is developed, in which the carbonized wood has a vertical pore structure that can provide attachment sites for the hygroscopic salt. The water adsorbed by ZnCl₂ is driven along the vertical pore channels to the photocatalyst due to the photothermal conversion effect. The bi‐phase interfaces of vapor/photocatalyst/hydrogen produced by the photothermal‐photocatalytic system significantly reduce the interface barrier and substantially lower the resistance to hydrogen transport. CW550 exhibited a water uptake of 0.56 g g⁻¹ and hydrogen yield of 21.99 µmol cm⁻² under 100 mW cm⁻² illumination at a flow rate of 2 mL min⁻¹ for 5 h and a half at atmospheric pressure.