Dual-Function Nanosheets for Water Treatment and H2 Production

Harnessing solar energy to split water and make hydrogen fuel is a promising sustainable process. However, the reaction can be slow even when catalysts are used. In some cases, alcohols or sugars are added to boost the rate of hydrogen production, but these chemicals are destroyed as hydrogen is generated, compromising the sustainability of the process. One alternative could be using contaminants in wastewater to enhance hydrogen-fuel generation. Titanium-based catalysts, for example, can both remove contaminants and generate hydrogen. However, the efficiencies are lower than expected for both steps because of their overlapping reaction sites. One way to reduce such interferences is to make catalysts with two separated sites for the two reactions.

Chuanhao Li, Sun Yat-sen University, Guangzhou, China, and colleagues have combined cobalt oxide and titanium dioxide to create a dual-functioning catalyst that breaks down common pharmaceuticals in wastewater, while also efficiently converting water into hydrogen for fuel. To make the catalyst, the researchers coated TiO₂ nanosheets with a thin layer of photodeposited Co₃O₄, using Co(NO₃)₂ as the precursor. Initial tests showed that this material did not produce much hydrogen, so as a next step, the team spiked this dual catalyst with 1 wt% of platinum nanoparticles—an efficient but expensive catalyst for generating hydrogen.

In the presence of simulated sunlight, the catalyst degraded pharmaceuticals such as enrofloxacin, ciprofloxacin, and ibuprofen, and produced substantial amounts of hydrogen. Finally, the team tested their product on real wastewater, water from a river in China, and deionized water samples. Under simulated sunlight, the catalyst stimulated hydrogen production in all three samples. The greatest amount of hydrogen was obtained from the wastewater sample. According to the researchers, the work provides a promising approach for sustainable water treatment.