Engineering the Photocatalytic Performance of B-C3n4@Bi2s3 Hybrid Heterostructures for Full‐Spectrum‐Driven Cr(Vi) Reduction and In-Situ H2o2 Generation: Experimental and Dft Studies

Abstract

Graphitic carbon nitride (g-CN) has been a promising metal-free catalyst for environmental remediation. However, its practical applications are limited by insufficient solar-light responsivity. Hetero-element doping and the construction of heterostructures comprised of g-CN and other band-matched semiconductors are considered to provide a means of overcoming these drawbacks. In the present work, a series of 2D/3D heterostructures comprised of a few layers of boron-doped g-CN (B-CN) anchored on sea urchin-like Bi 2 S 3 (BS) particles (B-CN@BS) were successfully synthesized. The catalytic performances of B-CN@BS composites were assessed for the photo-reduction of Cr(VI) and in-situ generation of H 2 O 2 under solar-light illumination. A binary composite containing 10 wt% of B-CN (B-CN@BS-10) achieved a photo-reduction of Cr(VI) with a rate of 99.4% during 150 min, which was 32.6- and 8.7-fold those of pure BS and B-CN, respectively. Interestingly, BS particles not only acted as an excellent co-catalyst to broaden the optical window from UV–vis to near-infrared (NIR), but also provided a large active surface area that enhanced the migration of charge-carriers between heterointerface, and suppressed charge recombination, thus improving the photocatalytic activities of B-CN@BS composites. Density functional theory calculations were performed to confirm that N atoms were appropriately replaced with boron atoms in the carbon nitride framework that demonstrated replacing nitrogen with boron is beneficial to tuning the energy band levels of B-CN. Moreover, B-CN@BS-10 had greater photocatalytic activity for H 2 O 2 generation that was ~16.4 and 2.5 times higher than that of bare BS and B-CN, respectively. Assisted by the ultraviolet photoelectron spectroscopy and electron spin resonance analyses, the charge-carrier pathway and possible photocatalytic mechanism were systematically studied.

Keywords: Photocatalysis, Hybrid heterostructure, Interfacial contact, Environmental remediation, Charge separation, DFT