Facet-dependent synthesis of H₂O₂ from H₂ and O₂ over single Pt atom-modified Pd nanocrystal catalysts

Hydrogen peroxide (H₂O₂) is one of the most valuable clean energy sources with a rapidly growing requirement in industry and daily life. The direct synthesis of H₂O₂ from hydrogen and oxygen is considered to be an economical and environmentally friendly manufacturing route to replace the traditional anthraquinone method, although it remains a formidable challenge owing to low H₂O₂ selectivity and production. Here, we report a catalyst consisting of Pd(111) nanocrystals on TiO₂ modified with single Pt atoms (Pt₁Pd(111)/TiO₂), which displays outstanding reactivity, producing 1921.3 μmol of H₂O₂, a H₂ conversion of 62.2% and H₂O₂ selectivity of 80.3% over 30 min. Kinetic and isotope experiments confirm that the extraordinary catalytic properties are due to stronger H₂ activation (the rate-determining step). DFT calculations confirm that Pt₁Pd(111) exhibits lower energy barriers for H₂ dissociation and two-step O₂ hydrogenation, but higher energy barriers for side reactions than Pt₁Pd(100), demonstrating clear facet dependence and resulting in greater selectivity and amount of H₂O₂ produced.