Transition-metal selenides have been evidenced to be promising candidates for efficient H₂ evolution cocatalysts due to a similar Se–H_ads (273 kJ/mol) bond energy to Pt–H (251 kJ/mol), while their H₂ evolution activity is still limited by the insufficient exposure of active Se atoms. Herein, a synergic idea of selenium-rich configuration and amorphization was developed to construct selenium-rich amorphous CoSe_1+x nanodots for maximum exposure of more hydrogen-production selenium sites. For this purpose, the selenium-rich amorphous CoSe_1+x nanodots with an ultrasmall size (0.2–1 nm) and selenium-rich character can be resourcefully and uniformly grafted with a TiO₂ photocatalyst via the facile photoinduced electron-reduction way. Photocatalytic results showed that the as-prepared selenium-rich a-CoSe_1+x/TiO₂(0.5 wt %) attains a maximal hydrogen production activity (3400 μmol h^–1 g^–1, AQE = 16.3%), which is significantly superior to those of crystalline c-CoSe/TiO₂ and conventional amorphous a-CoSe/TiO₂ samples by a factor of 3.2 and 1.6 times, respectively. The outstanding activity can be ascribed to the cooperation of accelerated photoinduced electron migration from TiO₂ to a-CoSe_1+x and rapid hydrogen evolution on the enriched active Se sites. Meaningfully, the selenium-rich a-CoSe_1+x can also be employed as the general H₂ evolution electron cocatalyst for CdS and g-C₃N₄ photocatalysts. This work sheds light on the ingenious design and construction of efficient and inexpensive active-site-rich cocatalysts for highly active photocatalytic materials.

中文翻译：

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富硒构型和非晶化协同最大化 CoSe _{1+ x}纳米点的活性中心量以实现高效的光催化 H ₂演化

由于与Pt-H (251 kJ/mol)相似的 Se-H _ads (273 kJ/mol) 键能，而它们的 H ₂析出活性，过渡金属硒化物已被证明是有效的 H ₂析出助催化剂的有希望的候选物仍然受到活性 Se 原子暴露不足的限制。在此，开发了富硒构型和非晶化的协同思想，以构建富硒非晶 CoSe _{1+ x}纳米点，以最大限度地暴露更多产氢硒位点。为此，具有超小尺寸（0.2-1 nm）和富硒特性的富硒无定形 CoSe _{1+ x}纳米点可以与 TiO ₂光催化剂通过简单的光致电子还原方式。光催化结果表明，所制备的富硒 a-CoSe _{1+ x} /TiO ₂ (0.5 wt %) 达到了最大的制氢活性（3400 μmol h ^–1 g ^–1，AQE = 16.3%），这是显着的分别优于结晶 c-CoSe/TiO ₂和常规非晶 a-CoSe/TiO ₂样品的 3.2 倍和 1.6 倍。出色的活性可归因于加速光诱导电子从 TiO ₂迁移到 a-CoSe _{1+ x}的协同作用富硒活性位点上的快速析氢。有意义的是，富硒a-CoSe _{1+ x}也可用作CdS 和gC ₃ N ₄光催化剂的通用H ₂析出电子助催化剂。这项工作阐明了用于高活性光催化材料的高效且廉价的富含活性位点的助催化剂的巧妙设计和构建。