Deciphering the photoelectrochemical behaviour of MoSe2-decorated BiVO4 as a dual system for concurrent degradation of methylene blue and hydrogen generation

Abstract

Green hydrogen production through photoelectrochemical (PEC) water splitting offers a sustainable energy solution, but the utilization of low-quality water is essential to conserve freshwater resources. Repurposing industrial wastewater, a substantial global issue, for PEC water splitting remains underexplored due to challenges in photoelectrode efficiency and stability. In this study, we present a MoSe2-decorated BiVO4 heterostructured photoelectrode (MoSe2/BiVO4 or BM) for green hydrogen production and efficient wastewater treatment. The optimized system yields a hydrogen production rate of 0.113 mmol from synthetic textile water (utilizing methylene blue as a model pollutant) while achieving a 94.74% degradation of pollutants. Synthesized via a hydrothermal route, BM demonstrates a high photocurrent density of 2.57 mA/cm2 at 1.23 V vs RHE, surpassing BV alone (0.14 mA/cm2). Further, BM shows incident photon to current efficiency (IPCE) of 12.24% and applied bias to photocurrent efficiency (ABPE) of 0.59%. Scavenger studies elucidate the role of holes in MB degradation. Tested in textile wastewater treatment outlets, BM exhibits a hydrogen production rate of 6.155 μmoles alongside reduced COD, BOD, TOC, and microbial load, showcasing its dual capability for hydrogen generation and simultaneous wastewater treatment. Thus, the efficiently designed type-II heterostructure formed between BV and MS behaves as a dual system with demonstrated usage in low-quality water for hydrogen generation with its simultaneous treatment.