Purifying the Air with Photocatalysis: Developing Bismuth Oxybromide/ Copper Phthalocyanine Composite Photocatalyst Filters with Enhanced Activity for NO_x Removal

Abstract The utilization of photocatalysis is a promising new strategy for reducing the substantially high levels of nitrogen oxides (NO x ) pollution in cities. In this work, we examine bismuth oxybromide (BiOBr) as a viable substitute due to its narrower band gap and high stability. Powders were synthesised using co‐precipitation, solvothermal and hydrothermal synthesis methods, resulting in particles with various morphologies including microcubes, microspheres, microflowers, clusters and microsquares. Their photocatalytic activities being evaluated in accordance with ISO 22197–1 : 2016 protocol under UV and visible light. The samples exhibiting the highest performance were produced by co‐precipitation, showing ~7 % NO and ~2 % NO x removal under visible light and ~19 % NO and ~10 % NO x removal under UV light. The activity was further enhanced, by incorporating copper(II) phthalocyanine (CuPc) through an impregnation method, where the optimal loading of 0.01 mol% surpassed the activity of the benchmark photocatalyst TiO 2 P25, with ~22 % NO and ~9 % NO x removal under visible light and ~40 % NO and ~23 % NO x under UV light. We anticipate that these BiOBr/CuPc photocatalyst filters can be applied within air purification systems and powered using less energy intensive visible light sources to remedy air pollution.