The construction of dual-type heterojunction photocatalysts for efficient hydrogen (H2) production through water splitting is a promising method in the field of photocatalysis. In this work, a ternary photocatalyst of g-C3N4/CoAl-LDH@MIL-53(Fe) with a dual S-scheme heterojunction was prepared for the first time. This composite demonstrates outstanding photocatalytic performance under visible light, reaching as high as H2 production rate of 1222.2 µmol·g−1·h−1 for the optimized g-C3N4/CoAl-LDH40@MIL-53(Fe)(60), which was 7.1 times higher than that of the single heterojunction CoAl-LDH40@MIL-53(Fe). The dual heterojunction design narrows the bandgap, increases photocurrent density, and reduces photoluminescence intensity, thereby improving visible light absorption and charge carrier separation. MIL-53(Fe) serves as excellent electron donor, while CoAl-LDH and g-C3N4 act as electron acceptors, which synergistically facilitate electron transfer in CoAl-LDH@MIL-53(Fe). Furthermore, the tight contact interface of g-C3N4/CoAl-LDH@MIL-53(Fe) establishes a dual S-scheme charge carrier transfer pathway with abundant active sites which are pivotal for the efficient separation of electrons and holes. A plausible mechanism for the photocatalytic water splitting to H2 was proposed, elucidating the role of the dual S-scheme heterojunction in boosting H2 production. Current work provides a promising strategy for fabricating dual heterojunction photocatalyst to achieve efficient photocatalytic H2 evolution.

中文翻译：

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构建双 S 型异质结 g-C3N4/CoAl-LDH@MIL-53（Fe） 三元光催化剂以增强光催化 H2 析出


构建双型异质结光催化剂，通过分解水高效生产氢气 （H2） 是光催化领域一种很有前途的方法。在这项工作中，首次制备了具有双 S 型异质结的 g-C3N4/CoAl-LDH@MIL-53（Fe） 三元光催化剂。该复合材料在可见光下表现出优异的光催化性能，优化的 g-C3N4/CoAl-LDH40@MIL-53（Fe）（60） 的 H2 生成速率高达 1222.2 μmol·g−1·h−1，比单一异质结 CoAl-LDH40@MIL-53（Fe） 高 7.1 倍。双异质结设计缩小了带隙，增加了光电流密度，降低了光致发光强度，从而提高了可见光吸收和电荷载流子分离。MIL-53（Fe） 是优良的电子供体，而 CoAl-LDH 和 g-C3N4 是电子受体，协同促进 CoAl-LDH@MIL-53（Fe） 中的电子转移。此外，g-C3N4/CoAl-LDH@MIL-53（Fe） 的紧密接触界面建立了具有丰富活性位点的双 S 型电荷载流子转移途径，这对于电子和空穴的有效分离至关重要。提出了一种光催化分解水成 H2 的合理机制，阐明了双 S 型异质结在促进 H2 产生中的作用。目前的工作为制备双异质结光催化剂以实现高效的光催化 H2 析出提供了一种有前途的策略。