# Mono-(Ni, Au) and Bimetallic (Ni-Au) Nanoparticles-Loaded ZnAlO Mixed Oxides as Sunlight-Driven Photocatalysts for Environmental Remediation

## TL;DR

Researchers developed a new photocatalyst using metal nanoparticles on a ZnAlO matrix that efficiently breaks down pollutants like bisphenol A under sunlight.

## Contribution

The study introduces a novel synthesis method for bimetallic Ni-Au nanoparticles on ZnAlO for enhanced photocatalytic performance under sunlight.

## Key findings

- Bimetallic Ni-Au@ZnAlO achieved 95% bisphenol A degradation after 180 minutes under simulated solar irradiation.
- The bimetallic system showed better performance than monometallic Ni@ZnAlO and Au@ZnAlO due to efficient charge separation and narrower band gap.
- NPs@ZnAlO nanocomposites inherited a nanoplate-like morphology from LDH precursors.

## Abstract

A facile and versatile strategy to obtain NPs@ZnAlO nanocomposite materials, comprising controlled-size nanoparticles (NPs) within a ZnAlO matrix is reported. The mono-(Au, Ni) and bimetallic (Ni-Au) NPs serving as an active phase were prepared by the polyol-alkaline method, while the ZnAlO support was obtained via the thermal decomposition of its corresponding layered double hydroxide (LDH) precursors. X-ray diffraction (XRD) patterns confirmed the successful fabrication of the nanocomposites, including the synthesis of the metallic NPs, the formation of LDH-like structure, and the subsequent transformation to ZnO phase upon LDH calcination. The obtained nanostructures confirmed the nanoplate-like morphology inherited from the original LDH precursors, which tended to aggregate after the addition of gold NPs. According to the UV-Vis spectroscopy, loading NPs onto the ZnAlO support enhanced the light absorption and reduced the band gap energy. ATR-DRIFT spectroscopy, H2-TPR measurements, and XPS analysis provided information about the functional groups, surface composition, and reducibility of the materials. The catalytic performance of the developed nanostructures was evaluated by the photodegradation of bisphenol A (BPA), under simulated solar irradiation. The conversion of BPA over the bimetallic Ni-Au@ZnAlO reached up to 95% after 180 min of irradiation, exceeding the monometallic Ni@ZnAlO and Au@ZnAlO catalysts. Its enhanced activity was correlated with good dispersion of the bimetals, narrower band gap, and efficient charge carrier separation of the photo-induced e−/h+ pairs.