Atomic Sulfur Filling Oxygen Vacancies Optimizes H Absorption and Boosts the Hydrogen Evolution Reaction in Alkaline Media. (7th May 2021) - Jin, Jing
Abstract: The hydrogen evolution reaction (HER) usually has sluggish kinetics in alkaline solution due to the difficulty in forming binding protons. Herein we report an electrocatalyst in which sulfur atoms are doping in the oxygen vacancies (VO ) of inverse spinel NiFe2 O4 (S‐NiFe2 O4 ) to create active sites with enhanced electron transfer capability. This electrocatalyst has an ultralow overpotential of 61 mV at the current density of 10 mA cm −2 and long‐term stability of 60 h at 1.0 Acm −2 in 1.0 M KOH media. In situ Raman spectroscopy revealed that S sites adsorb hydrogen adatom (H*) and in situ form S‐H*, which favor the production of hydrogen and boosts HER in alkaline solution. DFT calculations further verified that S introduction lowered the energy barrier of H2 O dissociation. Both experimental and theoretical investigations confirmed S atoms are active sites of the S‐NiFe2 O4 . Abstract : Sulfur‐atom doping of inverse spinel NiFe2 O4 results in the occupation of the oxygen vacancies. S sites in the S‐NiFe2 O4 likely adsorb H adatoms and form S‐H* in situ, which boosts the hydrogen evolution reaction (HER) in alkaline solution. DFT calculations further verified that the lowered energy barrier for H2 O dissociation induced by S doping is the key reason for the remarkable HER performance.