Synergistic Role of Substitutional Au and S-Vacancies in MoS2 in Catalyzing Direct Synthesis of Hydrogen Peroxide: First-Principles Analysis

Hydrogen peroxide (H2O2), a highly reactive molecule owing to its unstable peroxide bond, is commonly used as an oxidizing, bleaching, and antiseptic agent. Direct synthesis of H2O2 (DSHP) is a controlled and efficient alternative to the current route for its commercial production using the anthraquinone auto-oxidation process. Presently, materials which catalyze DSHP suffer from the issues of selectivity and reusability. Here, we demonstrate Au-substituted (at S sites) 1H-MoS2 with S-vacancies (AuxMoS2-x-v ) as an efficient and selective catalyst for DSHP. Using first-principles calculations, we show that Au-x MoS2-x-v catalyzes formation of all intermediates along the reaction path of DSHP with no significant energy barriers, accompanied by only weak structural reconstruction of the catalyst which augurs well for its cyclability. High selectivity of AuxMoS2-x-v is evident in low activation energy barriers along reaction steps, specifically toward DSHP. We uncover the mechanisms of synergistic roles of substitutional Au and S-vacancies that facilitate efficient two-electron hydrogenation of O-2 to H2O2.