Quartz-Driven Quartz@WO3 Piezocatalyst for Hydrogen Evolution Reaction

Piezocatalyst is one of the most innovative catalysts for hydrogen evolution reaction in these years. It has attracted broad interest due to its ultra-high efficiency and renewability. In this study, we initiatively fabricate single-crystal quartz microrods (Quartz MRs) from rice husks, which possess excellent piezoelectricity. Firstly, the raw rice husks are washed and acidized with HCl solution for several hours, following by calcination at 550℃ for 6 hours to produce highly porous SiO 2 (RH-SiO 2 ) that serves as the precursor of quartz MRs. After that, some NaCl and 0.6M NaOH solution are mixed with the as-synthesized RH-SiO 2 . The final mixture is then poured into the Teflon-lined stainless-steel autoclave, undergoing hydrothermal process at 220℃ for 12 hours. To form the Quartz@WO 3 heterostructure, Na 2 WO 4 ·2H 2 O and citric acid are dissolved in DI water and the pH value is adjusted to 1.0 under stirring. After the solution is formed, the as-prepared quartz MRs are added into it and sealed in an autoclave, placing in the oven at 120℃ for 3 hours. Finally, the product is calcined to remove residual water and we can obtain the Quartz@WO 3 heterostructure. The crystal structures of Quartz MRs and WO 3 are well identified by XRD analysis, which corresponds to alpha quartz and monoclinic WO 3 respectively. Though gas chromatography (GC) analysis, the hydrogen generation rate of Quartz@WO 3 effectively enhances around 53% compared to that of pristine WO 3 under ultrasonication as an external mechanical force, this may be associated with the piezoelectric effect from the quartz MRs.