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

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 TiO₂ 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.