Revealing the role of tellurium in palladium-tellurium catalysts for the direct synthesis of hydrogen peroxide

•H2O2 synthesis was markedly promoted by modifying the Pd catalyst with Te.•The origin of active sites has been revealed by experimental and DFT methods.•High-energy step sites have proved to be unfavorable for H2O2 synthesis.•Te promotes H2O2 synthesis by blocking high-energy sites and forming Pd-Te sites.