S-Scheme Co₉S₈ Nanoflower/Red Phosphorus Nanosheet Heterojunctions for Enhanced Photocatalytic H₂ Evolution

Environmental and energy problems can be effectivelyalleviatedby solar photocatalysis technology. In this work, an S-scheme Co9S8 nanoflower/RP nanosheet heterojunction was fabricatedusing a solvothermal solvent evaporation strategy for effectivelyenhancing the photocatalytic H-2 evolution. The investigationshows that the introduction of spherical Co9S8 can not only increase the electrochemical active surface area, providemore photoinduced charges, and decrease the electrochemical impedanceof the composite system but also reduce the H-2 evolutionoverpotential, leading to a H-2 evolution rate of 1562.5 & mu;mol & BULL;h(-1)& BULL;g(-1) over1% Co9S8/RP sample, which is 8.2 and 18.9 timesthat of pure RP and Co9S8, respectively. Inaddition, the water contact angle of RP is obviously reduced from11.8 & DEG; to 3.1 & DEG; after introducing Co9S8; this superhydrophilic surface is conducive to the adsorption ofwater molecules on the catalyst surface. Further investigation showsthat Co9S8 and RP can form a built-in electricfield, which can accelerate the migration of photoexcited carriersfrom the conduction band of RP to the valence band of Co9S8 along the S-scheme path and reserve the highly activecharges. This work provides an effective strategy to design a low-cost,extremely active, and stable RP-based S-scheme heterojunction forphotocatalytic H-2 evolution.