Monovacant Janus WSSe designed as a bifunctional photocatalyst for OER and CO2RR with multiple C1 products

Abstract

The photocatalytic CO2RR is a promising strategy for carbon neutrality, while OER is a crucial half-reaction in energy storage and conversion processes, including water splitting, CO2RR and metal-air batteries. However, developing effective and eco-friendly photocatalysts remains challengeable. In this study, Janus WSSe with monovacant Se (VSe-WSSe) is designed as a bifunctional photocatalyst. Based on the evaluation of the thermodynamic stability and *CO2 capability, the light absorption and photocatalytic performance of CO2RR and OER are systematically investigated. In the lower energy range of visible light, VSe-WSSe has better light absorption than pristine WSSe, facilitating photocatalytic efficiency. As for CO2RR, all possible reaction pathways and multiple C1 products are explored, demonstrating that the products of HCOOH, CH3OH and CH4 have UL values of -0.97 V, -1.52 V and -1.57 V, respectively. The photogenerated electrons potential of 0.69 eV at pH=0 will reduce the UL values of CH3OH and CH4 to -0.83 V and -0.88 V, respectively. Moreover, the CO2RR can greatly suppress the competitive HER. The PDS of OER occurs at the step of H2O→*OH with UL= -1.57 V. The photogenerated holes potential of 1.57 eV can make all the hydrogenation steps go downhill and result in a spontaneous reaction. This research unveils the new possibility of monovacant Janus WSSe as a bifunctional photocatalyst for CO2RR and OER, which opens the application avenue of Janus materials.