Sonolytic and Ultrasound-Assisted Hydrogen Production: Insights, Trends, and Future Perspectives

Abstract

This study employs the bibliometric review method to assess the evolution of research in sonolytic and ultrasound-assisted hydrogen production between 2000 and 2025 using data from the Scopus database. The study found research done so far as a dynamic, cross-disciplinary field driven by global decarbonization and technological innovation. Keyword and thematic mapping identified a central focus towards maximizing the hydrogen evolution reaction (HER) with the assistance of ultrasound catalysis, with advanced materials like gC3N4, TiO2, and quantum dots. Emerging themes of piezocatalysis, biohydrogen, and ultrasonication-enhanced pretreatment indicate a trend towards multifunctional, sustainable, and bio-integrated processes. The clustering analysis identified distinct strategic research directions, including visible-light-driven heterojunctions, anticorrosion electrodes, ultrasonic fermentation, and hybrid catalytic systems integrating sonochemistry with photocatalysis, electrocatalysis, and thermochemical reforming. Non-noble metal catalysts and nanostructures enabled by sonication are especially gaining prominence owing to their efficiency and scalability. The countrylevel analysis revealed a commanding position for China, with growing contributions from India, South Korea, and strategic international collaborations. Together, the field is transitioning from fundamental research to application-oriented innovation, and the future opportunity rests in scalable, hybrid systems that integrate ultrasonic, optical, and biochemical processes. These findings suggest that ultrasound-assisted hydrogen generation may contribute to advances in sustainable energy technologies and potential industrial implementation.