Probe sonication to prepare homogenous WO3 nanosheet 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, CO 2 catalysis, ammonia production, etc. Solvothermal synthesis is a cost-effect method to produce large quantities of WO 3 nanoparticles, however, the crystal phases and structures are sensitive to the synthesis procedure. The quality and performance of WO 3 thin film reply on the quality of WO 3 nanoparticles. To improve the homogeneity and repeatability of WO 3 solvothermal synthesis and thin film fabrication, we prepared homogeneous WO 3 ink based on probe sonication of as-synthesized WO 3 nanosheets in isopropanol. We further studied the influence of precursors in the solvothermal synthesis in the presence of oxalic acid. From the as-prepared WO 3 ink, we developed an optimized protocol to fabricate WO 3 thin films with good repeatability by spin-coating.