Employing a single cocatalyst to concurrently mediate reactions with electrons and those with holes toward efficient and stable photocatalysts is highly desirable yet challenging. Herein, two-dimensional (2D) in-plane CdS/Ti₃C₂T_x sheet-onto-sheet heterostructures have been deliberately constructed, in which Ti₃C₂T_x, a prototype MXene, is demonstrated to act as a Janus cocatalyst for simultaneously promoting electron-driven photoreduction reaction and inhibiting hole-induced photocorrosion of semiconductor CdS. Ti₃C₂T_x serves as an electron mediator to boost the electron extraction from CdS for photoreduction reactions. The interlayer assembly maintains the accessible surface reaction sites of CdS, while concomitantly the Cd²⁺ confinement effect of Ti₃C₂T_x retards the oxidative holes induced photocorrosion of CdS through preventing Cd²⁺ leaching. As a result, the photoactivity and stability of CdS are concurrently enhanced through coupling with Ti₃C₂T_x as a Janus cocatalyst. This facile and double-gain strategy is expected to present a conceptual approach to the rational design of efficient and stable photocatalysts toward solar energy conversion.

非常希望使用单一助催化剂同时介导与电子和那些具有空穴的反应，以产生有效和稳定的光催化剂。在这里，二维（2D）平面内CdS / Ti ₃ C ₂ T _x层到层异质结构被刻意地构造，其中Ti ₃ C ₂ T _x，原型MXene，被证明充当Janus助催化剂，可同时促进电子驱动的光还原反应并抑制半导体CdS的空穴诱导的光腐蚀。钛₃ C ₂ T _x用作电子介体以促进从CdS中提取电子以进行光还原反应。中间层组件保持了CdS的可及表面反应位点，同时Ti ₃ C ₂ T _x的Cd ²⁺限制作用通过防止Cd ²⁺浸出而延迟了氧化空穴对CdS的光腐蚀作用。结果，通过与Ti ₃ C ₂ T _x偶联同时增强了CdS的光活性和稳定性。作为Janus助催化剂。期望这种简便且双增益的策略将提出一种概念性方法，以合理设计高效，稳定的光催化剂，以实现太阳能转化。