Pt quantum dots deposited on N-doped (BiO)2CO3: enhanced visible light photocatalytic NO removal and reaction pathway

Abstract

In order to achieve efficient photocatalytic NO removal, N-doped (BiO)₂CO₃ hierarchical superstructures deposited with Pt quantum dots (2–4 nm) were fabricated by a one-pot hydrothermal method using ammonium bismuth citrate and H₂PtCl₆ as precursors. In such a combined way, visible light absorption and charge carrier separation can be simultaneously enhanced. The as-prepared Pt/N-doped (BiO)₂CO₃ catalysts exhibited a highly enhanced visible-light photocatalytic performance for NO removal and phenol degradation, which can be ascribed to the N doping that narrows the band gap, the formation of a Schottky barrier because of Pt that promotes electron/hole separation, and scattering and surface reflecting effects (SSR) caused by the hierarchical architecture. To reveal the reaction mechanism of photocatalytic NO oxidation, in situ DRIFTS investigation was applied to probe the reaction process, and a new intermediate, NO⁺, was firstly discovered during photocatalysis. Pt quantum dot deposition could change the reaction pathway via the inhibition of NO₂ production. Based on ESR trapping and time-dependent observation of the reaction products, a new photocatalytic reaction pathway was proposed for photocatalytic NO oxidation with Pt/N-doped (BiO)₂CO₃. The present work could provide new perspectives for advancing the photocatalysis efficiency, offer a new insight into the photocatalytic NO oxidation process and promote large-scale environmental applications of high-performance photocatalysts.