In-situ photodeposition of cadmium sulfide nanocrystals on manganese dioxide nanorods with rich oxygen vacancies for boosting water-to-oxygen photooxidation

Abstract

Carrier separation and surface reaction kinetic are two main bottlenecks limiting photocatalytic efficiency of photocatalysts towards an industrial level. In this regard, heterostructures and defects engineering have been proven to be effective strategies for addressing the two issues. However, the integrated construction of heterostructures and defects has been reported rarely. Herein, a facile in-situ photodeposition strategy has been developed to grow CdS nanocrystals on MnO2-x nanorods with rich oxygen vacancies (VO) as a direct Z-scheme photocatalyst for boosting water oxidation. It has been found that the Cd2+ ions accept photoelectrons from MnO2-xunder irradiation for the in-situ growth of CdS nanocrystals, which enables a close contact between the two components, providing high-speed electron-transport channels for photocatalysis. Meanwhile, the photooxidation half reactions extract surface lattice oxygen, leading to the increase of VO content in MnO2-x, which supplies abundant active sites for oxygen evolution. Owing to the synergistic effects of VO and Z-scheme systems, the optimized MnO2-x/CdS photocatalyst displays a dramatically enhanced photocatalytic activity with an O2 production rate of 779 μmol g-1h-1 under visible-light irradiation without any cocatalysts, which is 2.33 times higher than the bare MnO2-x. This work reveals the cooperative manipulation of VO and CdS nanocrystals on MnO2-x for achieving efficient photocatalysis, providing new insights into the construction of high-performance photocatalysts via a combined strategy of Z-scheme heterostructures and surface defects.