Using density functional theory, corrected for on-site Coulomb interactions (DFT + U), we have investigated surface modification of TiO₂ with metal chalcogenide nanoclusters for hydrogen evolution. The nanoclusters have composition M₄X₄ (M = Sn, Zn; X = S, Se) and are adsorbed at the rutile (110) surface. The nanoclusters adsorb exothermically, with adsorption energies in the range −2.8 eV to −2.5 eV. Computed density of states (DOS) plots show that cluster-derived states extend into the band-gap of the rutile support, which indicates that modification produces a redshift in light absorption. After modification, photoexcited electrons and holes are separated onto surface and cluster sites, respectively. The free energy of H adsorption is used to assess the performance of metal chalcogenide modified TiO₂ as a catalyst for the hydrogen evolution reaction (HER). Adsorption of H at nanocluster (S, Se) and surface (O) sites is considered, together with the effect of H coverage. Adsorption free energies at cluster sites in the range −0.15 eV to 0.15 eV are considered to be favourable for HER. The results of this analysis indicate that the sulphide modifiers are more active towards HER than the selenide modifiers and exhibit hydrogen adsorption free energies in the active range, for most coverages. Conversely, the adsorption free energies at the selenide nanoclusters are only in the active range at low H coverages. Our results indicate that surface modification with small, dispersed nanoclusters of appropriately selected materials can enhance the photocatalytic activity of TiO₂ for HER applications.

使用密度泛函理论，校正现场库仑相互作用 (DFT + U)，我们研究了用于析氢的金属硫属化物纳米团簇对TiO _{2 的}表面改性。纳米团簇的组成为 M ₄ X ₄(M = Sn, Zn; X = S, Se) 并吸附在金红石 (110) 表面。纳米团簇以放热方式吸附，吸附能范围为 -2.8 eV 至 -2.5 eV。计算态密度 (DOS) 图显示，簇衍生的态扩展到金红石载体的带隙中，这表明修改会产生光吸收的红移。修饰后，光激发电子和空穴分别分离到表面和簇位点。H吸附自由能用于评价金属硫属化物改性TiO ₂的性能作为析氢反应（HER）的催化剂。考虑了 H 在纳米团簇 (S, Se) 和表面 (O) 位点的吸附，以及 H 覆盖率的影响。在-0.15 eV 到 0.15 eV 范围内的簇位点的无吸附能被认为有利于 HER。该分析的结果表明，对于大多数覆盖范围，硫化物改性剂比硒化物改性剂对 HER 更具活性，并且在活性范围内表现出氢吸附自由能。相反，硒化物纳米团簇的吸附自由能仅在低 H 覆盖率的活性范围内。Our results indicate that surface modification with small, dispersed nanoclusters of appropriately selected materials can enhance the photocatalytic activity of TiO ₂ for HER applications.