Bunga Nurkhalifah, Vera Pangni Fahriani, Sarah Dampang, Muhammad Fahmi Hakim, and Siti Nurhayati, “Improvement of TiO2 Performance with 10% Cu–TiO2/BiVO4 Heterojunction Composite Using Sonication in Photoelectrochemical Water Splitting”, J. Energy Mater. Instrum. Technol., vol. 6, no. 4, pp. 209–219, Nov. 2025.