Huijun Zhao has made significant contributions to the development of electrocatalysis, photoelectrocatalysis and thermocatalysis principles, and nanostructured catalysts for important reactions of solar energy conversion, batteries, fuel cells, hydrogen generation, nitrogen-fixation, biomass-derived platform compounds upgrading, environmental remediation, bactericidal and sensing applications. He has discovered a suite of photoelectrocatalysis-based sensing principles, and successfully transformed these discoveries into commercial instruments that have brought a paradigm shift for aquatic organic pollutants monitoring/assessment practice. Zhao has also established an array of catalyst activation principles to unlock the catalytic powers of nonprecious materials that address the shortfalls of catalysts for important catalysis reactions.