Cu Atomic Subnanoclusters on TiO<sub>2</sub> for Photocatalytic Hydrogen Evolution
Hanjun Zou, Yan Tong, Yajie Feng, Yongfeng Zhou, Jiaxun Xiao, Lu Xia, Anku Guha, Bárbara B. Polesso, Bin Zhang, Juanli Liu, Kaiwen Wang
Abstract
Subnanocluster (SNC) cocatalysts are considered to be promising cocatalysts for photocatalytic hydrogen evolution reaction (HER) due to their rich surface-active sites and high atom utilization efficiency. Herein, a reductant-mediated in situ growth of the atomic clusters procedure is developed to synthesize SNC-Cu serving as advanced cocatalysts on TiO 2 nanoparticles for HER. The optimized SNC-Cu/TiO 2 catalyst, with 1.8 wt % metal mass loading, exhibits a remarkable hydrogen evolution rate of 6832 μmol g –1 h –1, which is ca. 25-fold that of bare TiO 2 (273 μmol g –1 h –1 and comparable to that of 1 wt % Pt-modified TiO 2 (7754 μmol g –1 h –1 ). Meanwhile, decent photostability and recyclability are also certified via a 20 h durability test. Comprehensive electron microscopy and spectroscopy characterizations unveil that the outstanding performance of SNC-Cu/TiO 2 can be attributed to accelerated charge separation/transfer and suppressed photoinduced electron–hole recombination. Furthermore, in situ X-ray photoelectron spectroscopy and first-principle calculations reveal that the electron-localized SNC-Cu, with its abundant surface sites, facilitates *H adsorption and desorption, thus enhancing the HER activity significantly. This work highlights the promising potential of constructing noble-metal-free SNCs in semiconductors for photocatalytic HER.