Zhang Jiaming, Liu Kaiwei, Zhang Boyang, Zhang Jifang, Liu Meng, Xu Yao, Shi Ke, Wang Haifeng, Zhang Zihao, Zhou Peng, Ma Guijun
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, PR China.
School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, Guangdong 518055, PR China.
J Am Chem Soc. 2024 Feb 14;146(6):4068-4077. doi: 10.1021/jacs.3c12417. Epub 2024 Jan 30.
The synthesis of photocatalysts with both broad light absorption and efficient charge separation is significant for a high solar energy conversion, which still remains to be a challenge. Herein, a narrow-bandgap YTiOS (YTOS) oxysulfide nanosheet coexposed with defined {101} and {001} facets synthesized by a flux-assisted solid-state reaction was revealed to display the character of an anisotropic charge migration. The selective photodeposition of cocatalysts demonstrated that the {101} and {001} surfaces of YTOS nanosheets were the reduction and oxidation regions during photocatalysis, respectively. Density functional theory (DFT) calculations indicated a band energy level difference between the {101} and {001} facets of YTOS, which contributes to the anisotropic charge migration between them. The exposed Ti atoms on the {101} surface and S atoms on the {001} surface were identified, respectively, as reducing and oxidizing centers of YTOS nanosheets. This anisotropic charge migration generated a built-in electric field between these two facets, quantified by spatially resolved surface photovoltage microscopy, the intensity of which was found to be highly correlated with photocatalytic H production activity of YTOS, especially exhibiting a high apparent quantum yield of 18.2% (420 nm) after on-site modification of a Pt@Au cocatalyst assisted by NaS-NaSO hole scavengers. In conjunction with an oxygen-production photocatalyst and a [Co(bpy)] redox shuttle, the YTOS nanosheets achieved a solar-to-hydrogen conversion efficiency of 0.15% via a Z-scheme overall water splitting. Our work is the first to confirm anisotropic charge migration in a perovskite oxysulfide photocatalyst, which is crucial for enhancing charge separation and surface catalytic efficiency in this material.
合成具有宽光吸收和高效电荷分离性能的光催化剂对于实现高太阳能转换具有重要意义，然而这仍是一个挑战。在此，通过助熔剂辅助固态反应合成的具有特定{101}和{001}面共暴露的窄带隙硫氧化钇钛（YTOS）氧硫化物纳米片被发现具有各向异性电荷迁移特性。助催化剂的选择性光沉积表明，YTOS纳米片的{101}和{001}表面在光催化过程中分别是还原区和氧化区。密度泛函理论（DFT）计算表明，YTOS的{101}和{001}面之间存在能带能级差异，这有助于它们之间的各向异性电荷迁移。分别确定了{101}面上暴露的Ti原子和{001}面上的S原子为YTOS纳米片的还原中心和氧化中心。这种各向异性电荷迁移在这两个面之间产生了一个内建电场，通过空间分辨表面光电压显微镜进行了量化，发现其强度与YTOS的光催化产氢活性高度相关，特别是在NaS-NaSO空穴清除剂辅助下对Pt@Au助催化剂进行原位修饰后，在420 nm处表现出高达18.2%的表观量子产率。结合析氧光催化剂和[Co(bpy)]氧化还原穿梭体，YTOS纳米片通过Z型全水分解实现了0.15%的太阳能到氢能转换效率。我们的工作首次证实了钙钛矿氧硫化物光催化剂中的各向异性电荷迁移，这对于提高该材料中的电荷分离和表面催化效率至关重要。
