Controlling the Photocatalytic Activity and Benzylamine Photooxidation Selectivity of Bi₂WO₆ via Ion Substitution: Effects of Electronegativity

Abstract

Doping or ion substitution is often used as an effective strategy to improve photocatalytic activities of several semiconductors. Most frequently, the dopants provide extra states to increase light absorption, alter the electronic structure, or lower the carrier recombination. This work focuses on ion substitution in Bi 2 WO 6 , where the dopants modify band-edge potentials of the catalysts. Specifically, we investigate how the electronegativity (EN) of the dopant could be used to tune the band-edge potentials and how such changes influence the photocatalytic mechanism. Compared to Te that has a lower EN, I lowers the band-edge potentials. While substitutions with both ions enhance Rh B photodegradation and benzylamine photooxidation, the modified band potentials of I-doped Bi 2 WO 6 influence the benzylamine photooxidation pathway, resulting in higher selectivity. Additionally, substitution of I 7+ in the Bi 2 WO 6 lattice improves the morphologies, decreases the band-gap energy, and reduces the carrier recombination. As a result, I-doped Bi 2 WO 6 shows almost 3 times higher %conversion while maintaining 100% selectivity in the oxidative coupling of benzylamine. The findings here signify the importance of the choices of dopants on the photocatalytic reactions and would benefit the design of other related materials for such applications.

Unveiling dual catalysis enhancement of a pyridinium-containing Zn(ii) coordination polymer in aerobic photooxidation of organic substrates and selective photoreduction of CO2

“…[1][2][3][4] Among them, photooxidation of organic substrates and photoreduction of CO 2 have gained a lot of attention in the past decade, as these reactions not only provide a fundamental understanding of photocatalysis but also show promising practical applications. [5][6][7][8][9][10][11] For example, oxidative coupling of amines to imines, oxygenation of suldes to sulfoxides, oxidation of alcohols to carbonyl compounds, and dehydrogenation of Nheterocycles are several basic reactions in organic synthesis, which are also of signicant importance in the production of pharmaceuticals and ne chemicals. [12][13][14][15][16] Using light energy to drive these oxidation reactions is believed to be green, sustainable, and economical, especially with earth-abundant catalysts and molecular O 2 as an oxidant in air under mild conditions.…”