Enhanced Photocatalytic Hydrogen Evolution via Multi‐Scattering of Incident Light by Embedded Cellulose Nanocrystal Nanoparticles in Hybrid Hydrogels Containing g‐C ₃ N ₄ /Pt Nanosheets

Enhanced photocatalytic hydrogen (H 2 ) evolution is realized by improving light harvesting via the multiscattering of incident light from embedded cellulose nanocrystal (CNC) nanoparticles in hybrid hydrogels. Due to the different refractive indices of CNC nanoparticles and hybrid acrylate‐based hydrogels, instead of direct penetration through the hybrid hydrogels, the incident light can be multiscattered by the CNC nanoparticles in the hybrid hydrogels. It significantly improves the light harvesting capability and favors the photocatalytic H 2 evolution. In addition, the CNC nanoparticles possess a certain number of negative charges, which is beneficial for the efficient separation of photogenerated charge carriers and enhancement of H 2 evolution performance. Hence, the averaged H 2 evolution rate of hybrid hydrogels embedded with 0.5 wt% of CNC (CNC 0.5 ) can reach 2266 μmol g −1 h −1 , which is 154% of that of the hybrid hydrogels without CNC nanoparticles. Further increasing the amount of embedded CNC nanoparticles, the photocatalytic H 2 evolution is reduced. It can be attributed to the aggregation of nanoparticles, which reduces the specific surface area and lowers the light harvesting. Based on the improved H 2 evolution performance, the g‐C 3 N 4 /Pt hydrogels embedded with CNC nanoparticles can be used for H 2 production in areas rich in solar energy but lack of water.