Ultrathin layered 2D/2D heterojunction of ReS2/high-crystalline g-C3N4 for significantly improved photocatalytic hydrogen evolution

An ultrathin layered 2D/2D van der Waals heterojunction of ReS 2 /high-crystalline g-C 3 N 4 is reported to significantly improve photocatalytic H 2 production attribute to its efficient charge transport, strong visible light harvesting, and suppressed recombination of photogenerated carriers. • Ultrathin layered 2D/2D van der Waals heterojunction of ReS 2 /high-crystalline g-C 3 N 4 . • Efficient charge transport of highly crystalline g-C 3 N 4 by eliminating deep defects. • Strong visible light harvesting, and excellent conductivity of ReS 2 nanoflakes. • Synergistic effect of rapid charge separation and transfer in 2D/2D heterojunction. • Superior photocatalytic H 2 -evolution efficiency of 3.46 mmol g −1 h −1 . Fabricating efficient nanocatalysts with excellent visible light response, coupled with rapid charge separation and transfer efficiency is still the most challenge for solar-driven hydrogen (H 2 ) evolution. Herein, an ultrathin layered 2D/2D van der Waals heterojunction of ReS 2 /high-crystalline g-C 3 N 4 (CCN) is constructed for the first time to significantly boost photocatalytic H 2 production. The as-prepared optimized 15% ReS 2 /CCN exhibits the highest H 2 -evolution rate of 3.46 mmol g −1 h −1 under visible light irradiation, a 2.7 fold enhancements over that of pristine CCN and is also much higher than ReS 2 alone. The excellent photocatalytic performance of ReS 2 /CCN is mainly attributed to the efficient charge transport of highly crystalline CCN by eliminating deep defects, the strong visible light harvesting of ReS 2 nanoflakes, as well as the synergistic effect of an ultrathin layered 2D/2D heterojunction to rapidly enable charge-separation while inhibiting the charge recombination. This work provides an efficient photocatalyst for H 2 energy production, and sheds light on fundamental insight to a rational design of photo/electro nanocatalysts or heterojunction materials toward highly efficient photocatalyst.