Synergistic wide spectrum response and directional carrier transportation characteristics of Se/SnSe2/TiO2 multiple heterojunction for efficient photoelectrochemical simultaneous degradation of Cr (VI) and RhB

Abstract

Multiple heterojunction with the excellent directional transportation and wide spectrum response performances has drawn more attentions in photoelectrochemical (PEC) fields. Recently, Se and SnSe2 nanomaterials have attracted enthusiasms because of high electron mobility and narrow bandgap characteristics in modern semiconductor industries. Specially, the stable of Se/SnSe2/TiO2 multiple heterojunction was constructed by anodic oxidation and one-step CVD methods, and the simultaneous degradation of RhB and Cr (VI) mixed solution was studied by PEC process. According to optical, photoelectric and PEC performances, Se/SnSe2/TiO2 multiple heterojunction exhibits the optimal transient photocurrent density about of 0.94 mA cm−2 at 1.23 V (vs. RHE), which is 1.7, 1.4, 1.3 and 15.7 times than pure TiO2 NTs, Se/TiO2, SnSe2/TiO2 and Se/SnSe2/Ti heterojunctions. Se/SnSe2/TiO2 multiple heterojunction also presents the best efficiencies of PEC simultaneous removal RhB and Cr (VI) about of 95.3% and 72.6%, respectively. Se/SnSe2/TiO2 multiple heterojunction with the outstanding stability and repeatability is attributed to the broad spectrum absorption and efficient utilization performances, high carrier separation and transportation characteristics, multiple active sites and fast redox processes at surface/interface of electrodes, respectively. This work provides one reliable strategy via surface/interface engineering to construct the efficient multiple heterojunction structure, and investigates one new direction in PEC degradation field for SnSe2-based heterojunctions. Meantime, this work offers the scientific values for synchronous wastewater treatment and clean energy production fields.