Efficient H₂O splitting for H₂ evolution over the semiconductor photocatalyst is a crucial strategy in the field of energy and environment. Herein, cocatalyst‐free 2D–2D CdS/g‐C₃N₄ step‐scheme (S‐scheme) heterojunction photocatalysts are fabricated through in situ hydrothermal growth of 2D CdS nanosheets (NSs) on 2D g‐C₃N₄ NSs. The results clearly confirm that the binary CdS/0.7g‐C₃N₄ S‐scheme heterojunction shows the best H₂ production rate (15.3 mmol g⁻¹ h⁻¹) without using any cocatalyst, which is 3.83 times and 3060 times higher than those of pure CdS and g‐C₃N₄, respectively. The apparent efficiency of CdS/0.7g‐C₃N₄ at 420 nm is 6.86%. Importantly, the as‐prepared CdS/0.7g‐C₃N₄ S‐scheme heterojunction has good stability when continuously irradiated for 21 h. The improved stability and activity are attributed to the formation of the S‐scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. It is expected that the design of robust cocatalyst‐free CdS/g‐C₃N₄ 2D–2D S‐scheme heterojunction can become a promising approach to develop the highly active H₂ evolution systems based on various kinds of conventional semiconductor NSs.

中文翻译：

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原位制备鲁棒的无助催化剂的CdS / g-C3N4 2D-2D阶梯式异质结，实现高活性的H2释放

在能源和环境领域，有效的H ₂ O分解使H ₂在半导体光催化剂上逸出是至关重要的策略。在此，通过在2D g-C ₃ N ₄ NS上原位水热生长2D CdS纳米片（NSs），制备了无助催化剂的2D-2D CdS / g-C ₃ N ₄阶梯式（S-方案）异质结光催化剂。结果清楚地表明，二元CdS / 0.7g‐C ₃ N ₄ S方案异质结显示出最佳的H ₂生成速率（15.3 mmol g ^-1  h ^-1），而无需使用任何助催化剂，分别比纯CdS和g‐C ₃ N _4的助催化剂高3.83倍和3060倍。CdS / 0.7g-C ₃ N ₄在420 nm处的表观效率为6.86％。重要的是，连续照射21小时后，所制备的CdS / 0.7g-C ₃ N ₄ S方案异质结具有良好的稳定性。稳定性和活性的提高归因于S型异质结的形成，这可以显着加速表面反应的界面电荷分离。预计将设计出无助催化剂的强效CdS / gC ₃ N ₄2D–2D S方案异质结可能成为开发基于各种常规半导体NS的高活性H ₂演化系统的有前途的方法。