Compressive-strained rutile TiO2 enables O2 mono-hydrogenation for singlet oxygen electrosynthesis

Electrochemical O 2 activation offers a green approach for efficient synthesis of singlet oxygen ( 1 O 2 ). However, it is commonly determined by adsorption-dependent O 2 activation and transformation and can suffer from the sluggish desorption of surface-bound *OOH. Here we report an adsorption-independent O 2 activation pathway for 1 O 2 electrosynthesis via an O 2 mono-hydrogenation process on compressive-strained rutile TiO 2 (CSR-TiO 2 ). This CSR-TiO 2 achieved an 1 O 2 generation rate of 148.26 μmol l −1  min −1 with near 100% Faradaic efficiency, outperforming the strain-free counterpart (35.97 μmol l −1  min −1 ) and other previously reported materials. Such superior performance of CSR-TiO 2 stemmed from compressive strain, which can suppress the formation of reductive unsaturated sites for the O 2 adsorption and enhance the reductive ability of atomic hydrogen (H*), favouring the O 2 mono-hydrogenation pathway and bypassing the traditional surface-bound *OOH desorption pathway. The generated 1 O 2 could be utilized for the selective oxidation of thioanisole and its derivatives, offering a promising strategy for green organic synthesis.