Hydrogen production from photocatalytic water splitting has been considered as a promising way to convert solar energy into chemical energy. Herein, a novel photocatalyst was synthesized successfully by coupling two materials utilizing an in situ method. An all-solid-state 0D/2D contact direct Z-scheme heterojunction was constructed between Mn_0.2Cd_0.8S and CeO₂, which formed an ideal photocatalytic system. It is proved that an efficient separation and enhanced redox ability of photoinduced charges can be obtained by constructing a direct Z-scheme composite photocatalyst. The maximum photocatalytic H₂-generation rate of 8.73 mmol h^–1 g^–1 was obtained in the Na₂S/Na₂SO₃ aqueous solution, which was 119 times greater than that of CeO₂. The composition, microstructure, morphology, optical properties, behaviors of photoexcited electrons, and electrochemical properties were studied by utilizing a series of characterizations, including XRD, SEM, TEM, mapping, UV–vis, PL, and photocurrent. The results of XPS, XRD, and SEM before and after the photocataytic hydrogen evolution indicated that the composite is stable. Also, PL and photocurrent indicated the successful construction of a direct Z-scheme. In addition, a Z-scheme mechanism for the photocatalytic hydrogen evolution was proposed and discussed. This work will provide new insights in designing and constructing novel Z-scheme heterojunction photocatalysts.

中文翻译：

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用于光催化制氢的全固态0D / 2D Mn _0.2 Cd _0.8 S / CeO ₂直接Z方案的合理设计

光催化水分解制氢已被认为是将太阳能转化为化学能的一种有前途的方法。本文中，通过使用原位方法偶联两种材料成功地合成了新型光催化剂。在Mn _0.2 Cd _0.8 S和CeO ₂之间构建了全固态0D / 2D接触直接Z型异质结，形成了理想的光催化体系。证明了通过构建直接的Z-方案复合光催化剂可以有效地分离和增强光诱导电荷的氧化还原能力。Na _2中获得的最大光催化H ₂生成速率为8.73 mmol h ^–1 g ^–1S / Na ₂ SO ₃水溶液，是CeO _2的119倍。利用一系列特征，包括XRD，SEM，TEM，作图，UV-vis，PL和光电流，研究了组成，微观结构，形态，光学性质，光激发电子的行为和电化学性质。在光催化氢释放之前和之后的XPS，XRD和SEM结果表明该复合材料是稳定的。而且，PL和光电流表明成功构建了直接的Z方案。此外，提出并讨论了光催化氢逸出的Z方案机理。这项工作将为设计和构建新型的Z型异质结光催化剂提供新的见解。