Designing efficient visible-light-active photocatalysts is important for practical uses. Herein, strontium titanate (SrTiO₃), a wide-bandgap semiconductor, loaded with chromium (III) nanoclusters has been demonstrated as a visible-light-active photocatalyst driven by the reductant-to-band charge transfer (RBCT) mechanism. The action spectrum revealed that absorption at around 430 nm contributed considerably to the photocatalytic 2-propanol decomposition. The reaction mechanism in the Cr(III)-loaded SrTiO₃ system was studied by electron spin resonance (ESR) spectroscopy, electrochemical, and photoelectrochemical technique. We confirmed that the interfacial electron transfer (i.e., RBCT) from Cr(III) nanoclusters to the conduction band of SrTiO₃ initiated the photocatalytic reaction under visible-light irradiation. In this system, moreover, the Cr(III) nanoclusters acted as a catalytic site for the efficient oxidation reaction. The RBCT mechanism opens new opportunities for other efficient wide-bandgap semiconductors to be active under visible-light irradiation and is expected to be applicable for a wider range of applications.

设计有效的可见光活性光催化剂对于实际应用很重要。在此，负载有铬（III）纳米团簇的宽带隙半导体钛酸锶（SrTiO ₃）已被证明是由还原带间电荷转移（RBCT）机理驱动的可见光活性光催化剂。作用谱表明，在约430 nm处的吸收对光催化2-丙醇的分解有很大贡献。通过电子自旋共振（ESR）光谱，电化学和光电化学技术研究了负载Cr（III）的SrTiO ₃系统中的反应机理。我们证实了从Cr（III）纳米团簇到SrTiO ₃导带的界面电子转移（即， RBCT）在可见光照射下引发了光催化反应。此外，在该系统中，Cr（III）纳米簇充当有效氧化反应的催化位点。RBCT机制为其他有效的宽带隙半导体在可见光照射下激活提供了新的机会，并有望将其应用于更广泛的应用中。