Thermal Water Splitting on the WO₃ Surface: Experimental Proof

Here, the splitting of water from humidity at the surface of WO3 is reported. The production of hydrogen occurs under mild conditions at 300 °C in the presence of humidity. Using operando diffuse reflectance infrared Fourier transform spectroscopy and DC resistance measurements complemented with density functional theory calculations, it was possible to elucidate the temperature-dependent surface reactions of WO3 with humidity. By examining multiple different nanomaterials at 300 °C, it was found that the oxidation of the surface by humidity is generally valid for WO3. The evolution of hydrogen was detected using catalytic conversion measurements. In addition to the evolution of hydrogen, understanding the interaction between the surface and humidity is a prerequisite for the optimized use of WO3 for a wide array of applications, such as optical sensors or memristors.