S-scheme heterojunction BP/WO3 with tight interface firstly prepared in magnetic stirring reactor for enhanced photocatalytic degradation of hazardous contaminants under visible light

Black phosphorous (BP) has attracted extensive attention because of its unique properties, but the unstable structure restricts its practical application. Herein, exfoliated tungsten trioxide (WO3) was innovatively chosen to couple with BP nanosheets to form a novel 2D/2D heterojunction BP/WO3 through self-assembly process. Instead of conventional hydrothermal reactor without the stirring function or just simple mixing at room temperature and pressure, the magnetic stirring reactor was adopted to provide an inert gas atmosphere (N2) with high temperature and pressure (120 °C and 0.4 MPa), where the contact chance of BP and WO3 nanosheets would be improved greatly and then be pushed towards each other to form tighter interface. The establishment of S-scheme band structure was proved by the abundant existence of ·OH and ·O2– detected by radical scavenging experiments and EPR test. Besides, the electron injection from WO3 to BP under irradiation confirmed by XPS test can improve the chemical stability of BP much, and it further indicated the construction of S-scheme charge migration pathway between BP and WO3, which can achieve effective spatial separation of photogenerated e--h+ pairs without sacrifice of weakening the redox power of useful electrons and holes. As a result, the 6BP/WO3 showed enhanced photocatalytic performance with a removal ratio of 98.6% for tetracycline hydrochloride (TCH) and 93.2% for Cr(VI) within 60 min, respectively. This study provides new strategy to the design and preparation of efficient 2D/2D S-scheme photocatalyst with visible light responsive ability.