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Rational design and construction of efficient electro-catalysts is crucial for advancing water electrolyzer technologies. Herein, a multi-interphase MnO 2 -SnO 2 -RuO 2 heterostructure nanocomposite is synthesized by using a simple sol-gel technique for water electrolysis in acidic medium. The synthesized multi-interphase heterostructure has modified the local electronic structure of the composite material and thereby enhanced the adsorption of reaction intermediates onto its active sites. The synthesized nanocomposite exhibits an excellent performance for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). It requires overpotentials of 243 mV for the OER and 133 mV for the HER to achieve a current density of 10 mA cm −2 in the acidic medium. The synergistic electronic interactions and strong chemical bonding between MnO 2 , SnO 2 and RuO 2 adjust the chemisorption energies of hydrogen and oxygen intermediates, leading to the improved electro-catalytic activity. Moreover, in a two-electrode electrolysis setup, the MnO 2 -SnO 2 -RuO 2 nanocomposite requires a cell voltage of 1.63 V to deliver a current density of 10 mA cm - ² for the overall water splitting reaction. The decomposition potential has further decreased to 1.60 V after 37 h continuous electrolysis due to lowering down of the HER overpotential at cathode site. The overpotential for the HER is reduced due to the formation of a porous network produced by etching of the MnO 2 species. The porous network has facilitated easy diffusion of the electrolyte to the cathode surface, interacted strongly with the electrolyte, facilitated the electron transport kinetics, and thereby lowered down the overall water splitting potential. • A bi-functional multi-interphase MnO 2 -SnO 2 -RuO 2 heterostructure was synthesized via sol-gel approach. • MnO 2 -SnO 2 -RuO 2 heterostructure nanocomposite demonstrates the overpotential of 243 mV and 133 mV at 10 mA cm −2 for the OER and HER, respectively. • A low cell voltage of 1.63 V was achieved for overall water splitting at current density of 10 mA cm −2 in the acidic medium.
Singh et al. (Wed,) studied this question.