Wilson Anna A, Moss Benjamin, Riaz Aysha A, Kalha Curran, Thakur Pardeep K, Lee Tien-Lin, Regoutz Anna, Takata Tsuyoshi, Hisatomi Takashi, Domen Kazunari, Durrant James R
Department of Chemistry, Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom.
Resnik Centre for Sustainability, California Institute of Technology, Los Angeles, California 91125, United States.
J Am Chem Soc. 2025 Sep 24;147(38):34438-34448. doi: 10.1021/jacs.5c07521. Epub 2025 Sep 11.
Photocatalytic water splitting offers a scalable and potentially low-cost route for the production of renewable hydrogen. Recently, a state-of-the-art system based on flux-mediated Al-doped SrTiO, modified with Rh-Cr-based proton reduction and CoOOH water oxidation cocatalysts, achieved apparent quantum yields for unassisted water splitting of up to 93%. Herein, we focus on the role of Al doping and Rh-Cr-based cocatalyst deposition on the accumulation and reaction dynamics of the long-lived holes required to drive water oxidation. We employ in situ and operando photoinduced absorption spectroscopy (PIAS) under water splitting conditions complemented by X-ray photoelectron spectroscopy (XPS). XPS data indicate that Al doping suppresses surface Ti defect states, coinciding with a 5-fold increase in the accumulation of long-lived SrTiO holes observed by PIAS. Rh-Cr-based cocatalyst addition is observed to further enhance the yield and lifetime (s-10 s time scales) of these photoaccumulated holes, assigned to the efficient electron extraction by this cocatalyst. These photoaccumulated holes exhibit fast (ca. 1 s) and slow (ca. 10 s) decay phases. While the dominant fast phase is assigned to the desired water oxidation reaction, the slow phase is assigned to deeply trapped unreactive holes; the yield of these unreactive holes is suppressed by facet-selective photodeposition of cocatalysts or preillumination. These results provide key insights into how Al:SrTiO functionalized by Rh-Cr-based cocatalysts accumulates oxidizing holes with lifetimes long enough to drive the kinetically challenging water oxidation reaction, thus achieving remarkably high quantum efficiencies for overall water splitting, insights which can be applied in the design of future photocatalytic materials.
光催化水分解为可再生氢的生产提供了一种可扩展且潜在低成本的途径。最近，一种基于通量介导的铝掺杂钛酸锶（Al-doped SrTiO₃）的先进系统，通过基于铑 - 铬（Rh-Cr）的质子还原和氢氧化钴（CoOOH）水氧化共催化剂进行改性，实现了无辅助水分解的表观量子产率高达93%。在此，我们关注铝掺杂和基于Rh-Cr的共催化剂沉积对驱动水氧化所需的长寿命空穴的积累和反应动力学的作用。我们在水分解条件下采用原位和操作光致吸收光谱（PIAS），并辅以X射线光电子能谱（XPS）。XPS数据表明，铝掺杂抑制了表面钛缺陷态，这与PIAS观察到的长寿命SrTiO₃空穴积累增加5倍相吻合。观察到添加基于Rh-Cr的共催化剂可进一步提高这些光积累空穴的产率和寿命（在10⁻¹至10 s时间尺度），这归因于该共催化剂的有效电子提取。这些光积累空穴表现出快速（约1 s）和缓慢（约10 s）的衰减阶段。虽然主要的快速阶段归因于所需的水氧化反应，但缓慢阶段归因于深度捕获的无反应性空穴；这些无反应性空穴的产率通过共催化剂的面选择性光沉积或预照明得以抑制。这些结果为基于Rh-Cr的共催化剂功能化的Al:SrTiO₃如何积累寿命足够长以驱动动力学上具有挑战性的水氧化反应的氧化空穴提供了关键见解，从而实现了整体水分解的显著高量子效率，这些见解可应用于未来光催化材料的设计。
