Probe sonication to prepare homogenous WO₃nanosheet inks for energy conversion and biosensing applications

Reaching net zero emissions of carbon has become a global consensus. Electrochemical and photoelectrochemical catalysis has been considered as one of the solutions. Among these studies, tungsten oxide, consisted of earth abundant elements, has exhibit potential applications in terms of water splitting, CO2 catalysis, ammonia production, etc. Solvothermal synthesis is a cost-effect method to produce large quantities of WO3 nanoparticles, however, the crystal phases and structures are sensitive to the synthesis procedure. The quality and performance of WO3 thin film reply on the quality of WO3 nanoparticles. To improve the homogeneity and repeatability of WO3 solvothermal synthesis and thin film fabrication, we prepared homogeneous WO3 ink based on probe sonication of as-synthesized WO3 nanosheets in isopropanol. We further studied the influence of precursors in the solvothermal synthesis in the presence of oxalic acid. From the as-prepared WO3 ink, we developed an optimized protocol to fabricate WO3 thin films with good repeatability by spin-coating.