Visible-light responsive gold nanoparticle and nano-sized Bi2O3-x sheet heterozygote structure for efficient photocatalytic conversion of N2 to NH3

Jijoe Samuel Prabagar, Kumbam Lingeshwar Reddy, Dong-Kwon Lim*

Chin. J. Struct. Chem., 2025, 44(4), 100564. DOI: 10.1016/j.cjsc.2025.100564

April 1, 2025

Photocatalyst; Gold nanoparticle; Bismuth oxide; Oxygen vacancy; Nitrogen fixation

ABSTRACT

The advancement in catalysis techniques for sustainable environmental applications, particularly an alternative to the current Haber-Bosch process for NH3, has recently gained widespread attention. Although photocatalytic conversion of N2 to NH3 using solar energy is an eco-friendly method, it has the limitation of low quantum yield. Recently, 2D Bi-based photocatalysts which exhibit higher visible light absorption than TiO2 and higher stability than MXene have been an active research topic, and their performance can be enhanced through improved visible light absorption properties by incorporating plasmonic gold nanoparticles while nitrogen adsorption could be enhanced through oxygen vacancy (OV) processes. In the present study, we explore the application of 2D nano-sized Bi2O3x and gold nanoparticles for visible light photo generation of NH3. HRTEM and XPS reveal that the formation of AuNP and nano-sized Bi2O3x in AuNP/Bi2O3x heterozygote structure promotes the charge carrier mobility and charge transport at the interface, resulting in a 2.6-fold increase in the photocatalytic activity compared to micro-sized Bi2O3x with AuNP. The improved photocatalytic performance can be ascribed to significant enhancement of visible light absorption by plasmonic nanoparticles, fast charge transport and mobility (due to sheet morphology) and the N2 activation by OV in AuNP/Bi2O3x heterozygote. Through a systematic experimental investigation involving catalysts, concentration, pH, and scavengers, the highest photocatalytic performance was achieved with the heterozygote structures of AuNP/n-Bi2O3x under optimized conditions, yielding 432.5 μmol gcat−1 h−1 of NH3.

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