# Exploring the Influence of Carbonaceous Material on the Photocatalytic Performance of the Composites Containing Bi–BiOBr and P25 TiO2 for NOx Remediation

## TL;DR

Adding graphene oxide to a photocatalytic composite improves its ability to remove nitrogen oxides from the air.

## Contribution

The study introduces a new composite material with graphene oxide that significantly enhances NOx removal efficiency.

## Key findings

- The GO-based composite achieved 21.9% NO removal and 15% NO2 removal.
- GO improved charge separation, surface area, and light absorption in the composite.
- The composite outperformed its parent materials like P25 TiO2 and Bi–BiOBr.

## Abstract

The Bi–BiOBr–P25 TiO2 composite material exhibits high and synergistic improvements in the photocatalytic activity for nitrogen oxides (NOx  = NO + NO2) removal. Herein, the influence of adding carbonaceous material to this composite, namely graphene (G), graphene oxide (GO), carbon nanotubes (CNT), and buckminsterfullerene (F) is explored; all at 1 wt%. Samples are synthesised using a one‐pot solvothermal method. The structural and morphological properties, composition, and photocatalytic performance of all samples are examined using scanning electron microscopy, carbon–hydrogen–nitrogen elemental analysis, high‐resolution transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, attenuated total reflectance–Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, X‐ray photoelectron spectroscopy, N2 sorption at 77 K, photoluminescence spectroscopy, diffuse reflectance transient absorption spectroscopy), and photocatalytic testing against NOx gas in accordance with ISO protocol (22197‐1:2016). Among the studied carbonaceous composites, the composite including GO shows the highest performance toward NOx remediation. For reactions in NO gas, it shows a combined higher NOx removal rate (21.9%) than its parent materials P25 (8.7%), Bi–BiOBr (6.5%), and GO (0%). For reactions in NO2 gas, it shows a higher NOx removal rate (≈15%) than its parent materials P25 (≈10%), Bi–BiOBr (≈5%), and GO (0%).

Bi/BiOBr/P25 TiO2 composites are synthesized via a solvothermal method incorporating 1 wt% of a carbon‐based material (graphene oxide [GO], graphene, carbon nanotubes, or buckminsterfullerene). The GO–based composite exhibits the highest photocatalytic NOx removal efficiency (≈22% NO and ≈15% NO2) with these synergetic improvements attributed to increased charge separation, surface area, and light absorption.© 2025 WILEY‐VCH GmbH