Efficient Light-Driven Fuel Cell with Simultaneous Degradation of Pollutants on a TiO2 Photoanode and Production of H2O2 on a Gas Diffusion Electrode Cathode

Photoelectrochemical (PEC) reduction of O-2 to H2O2 via a two-electron reaction pathway is an attractive strategy for decentralized and sustainable H2O2 generation. However, the low selectivity, inadequate mass transfer efficiency of cathodic O-2 reduction, as well as the high overpotential of the anodic half-reaction of H2O oxidation together limit the efficiency of the PEC system. Here, an elaborately designed PEC system coupling O-2 reduction on a gas diffusion electrode (GDE) with organic pollutants oxidation on a TiO2 nanotube arrays (TNTs) photoanode is assembled for simultaneously tackling the aforementioned limitations. Benefiting from the synergistic effect between accelerated O-2 mass transfer and alleviated anodic overpotential, this PEC system exhibits a H2O2 generation rate of 34.7 mu mol L-1 h(-1) cm(-2) at the cathode, which is 3.49 times higher than that of the system with neither the GDE nor pollutants (9.93 mu mol L-1 h(-1) cm(-2)). Moreover, over 88% of pollutants, such as phenol and benzoic acid, can be degraded, and the mineralization rate can surpass 70% at the anode. This work proposes a new insight into developing a dual-functional PEC system for H2O2 production and simultaneous pollutants degradation.