This study describes the UV solution photodeposition of several earth-abundant 3d transition metals (Co, Ni, and Cu) onto the surface of nanoparticulate TiO₂. Irradiated methanolic metal dichloride solutions with suspended Degussa P25-TiO₂ (1–2 wt % metal to TiO₂) yield visibly colored titanias, whereas the bulk TiO₂ structure is unchanged; X-ray photoelectron spectroscopy confirms that metals are present on the titania surface in either reduced metal (Cu/Cu⁺) or metal cation states (Co²⁺ and Ni²⁺), and UV–vis diffuse reflectance spectroscopy shows new visible absorbance features. The analyzed bulk metal contents (∼0.04–0.6 at. %, highest for copper) are lower than the nominal metal solution content. Mixed-metal solution photodeposition reactions roughly parallel observations for single metals, with copper deposition being most favored. These 3d metal surface-modified titanias show significant (∼5–15×) improvement in UV photocatalytic H₂ evolution versus unmodified TiO₂. H₂ evolution rates as high as 85 μmol/h (8500 μmol h^–1 g^–1) were detected for Cu-coated TiO₂ using continuous monitoring of reactor headspace gases by portable mass spectrometry. Control experiments verify the necessity of the methanol sacrificial oxidant in both metal deposition and H₂ evolution. In situ metal surface deposition is quickly followed by enhanced H₂ evolution relative to TiO₂, but at lower levels than isolated metal surface-modified titanias. The photodeposited 3d metal species on the TiO₂ surface likely act to reduce electron–hole recombination by facilitating the transfer of photoinduced TiO₂ conduction band electrons to protons in solution that are reduced to H₂. This study demonstrates a facile method to modify photoactive TiO₂ nanoparticles with inexpensive 3d transition metals to improve photocatalytic hydrogen evolution, and it shows the utility of quantitative real-time gas evolution monitoring by portable mass spectrometry.

中文翻译：

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过渡金属表面改性 TiO2 增强光催化析氢

_{本研究描述了几种地球储量丰富的 3d 过渡金属（Co、Ni 和 Cu）的紫外溶液光沉积到纳米颗粒 TiO 2}表面上。用悬浮的 Degussa P25-TiO _{2 （金属占 TiO 2}的 1–2 wt% ）照射甲醇金属二氯化物溶液，产生明显有色的二氧化钛，而块体 TiO ₂结构未改变；^{X 射线光电子能谱证实金属以还原金属 (Cu/Cu +} ) 或金属阳离子态 (Co ²⁺和 Ni ²⁺ )存在于二氧化钛表面，紫外可见漫反射光谱显示新的可见吸收特征。分析的块体金属含量（~0.04–0.6 at.%，铜最高）低于标称金属溶液含量。混合金属溶液光沉积反应与单一金属的观察结果大致相同，其中铜沉积最受欢迎。与未改性的 TiO _{2相比，这些 3d 金属表面改性的二氧化钛在紫外光催化 H 2}析出方面表现出显着的（~5-15 倍）改进。使用便携式质谱仪连续监测反应器顶空气体，检测到 Cu 涂层 TiO ₂的H ₂释放速率高达 85 μmol/h (8500 μmol h ^–1 g ^{–1 )。}_{对照实验验证了金属沉积和H 2}析出中甲醇牺牲氧化剂的必要性。原位金属表面沉积很快就会出现相对于TiO _{2而言增强的H 2}释放，但其水平低于孤立的金属表面改性二氧化钛。_{TiO 2}表面上光沉积的3d金属物质可能通过促进光诱导TiO ₂导带电子转移到溶液中被还原为H ₂的质子来减少电子-空穴复合。本研究展示了一种用廉价的 3d 过渡金属修饰光活性 TiO ₂纳米粒子以改善光催化析氢的简便方法，并展示了便携式质谱仪定量实时气体析出监测的实用性。