Impact of Atomic Rearrangement and Single Atom Stabilization on MoSe2@NiCo2Se4 Heterostructure Catalyst for Efficient Overall Water Splitting

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-05, Vol.18 (19), p.n/a
• Main Authors: Majumdar, Abhisek, Dutta, Pronoy, Sikdar, Anirban, Lee, Heehyeon, Ghosh, Debasis, Jha, Sambhu Nath, Tripathi, Shilpa, Oh, Yongtak, Maiti, Uday Narayan
• Format: Article
• Language: English
• Subjects: Current density; Density functional theory; Electrolysis; Electronic control; Heterostructures; hydrogen evolution; Hydrogen production; Iridium; Metal oxides; Molybdenum compounds; Nanotechnology; oxygen evolution; Oxygen evolution reactions; Single atom catalysts; Water splitting
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202200622

High overpotentials required to cross the energy barriers of both hydrogen and oxygen evolution reactions (HER and OER) limit the overall efficiency of hydrogen production by electrolysis of water. The rational design of heterostructures and anchoring single‐atom catalysts (SAC) are the two successful strategies to lower these overpotentials, but realization of such advanced nanostructures with adequate electronic control is challenging. Here, the heterostructure of edge‐oriented molybdenum selenide (MoSe2) and nickel‐cobalt‐selenide (NiCo2Se4) realized through selenization of mixed metal oxide/hydroxide is presented. The as‐developed sheet‐on‐sheet heterostructure shows excellent HER performance, requiring an overpotential of 89 mV to get a current density 10 mA cm−2 and a Tafel slope of 65 mV dec−1. Further, resultant MoSe2@NiCo2Se4 is photochemically decorated with single‐atom iridium, which on electrochemical surface reconstruction displays outstanding OER activity, requiring only 200 and 313 mV overpotentials for 10 and 500 mA cm−2 current densities, respectively. A full cell electrolyzer comprising of MoSe2@NiCo2Se4 as cathode and its SAC‐Ir decorated counterpart as anode requires only 1.51 V to attain 10 mA cm−2 current density. Density functional theory calculation reveals the importance of rational heterostructure design and synergistic electronic coupling of single atom iridium in HER and OER processes, respectively. Atomic rearrangements via selenization and electrochemical self‐activation are used for the development of highly active catalysts to trigger overall water splitting at low operating voltage. The heterostructure comprised of edge‐exposed MoSe2 erected from NiCo2Se4 base displays excellent hydrogen evolution reaction performance, while its single‐atom iridium linked counterpart exhibits one of best oxygen evolution reaction performances, via in situ molybdenum dissolution and surface atomic reconstruction.