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

Abstract

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.

Theoretically revealing the activity origin of the hydrogen evolution reaction on carbon-based single-atom catalysts and finding ideal catalysts for water splitting

“…Especially for overall water splitting, bifunctional catalysts generally exhibit outstanding performance since the optimal working conditions for the two individual unfunctional catalysts generally differ. 4,58,59 Thus, the OER activity on the carbon-based SACs was also predicted, the SACs of Co/Rh/Ir-MOF, Co/Rh/Ir-Pc, Co/Rh-N-C, and Ni/Pd-C revealed the excellent OER performance comparable to IrO 2 , indicating excellent OER performance for Co, Ir, and Rh based SACs. Finally, the Co-N-C, Co-Pc, and Co/ Rh/Ir-MOF were found to be promising bifunctional SACs for both HER and OER.…”

Ruthenium nanoparticles supported on Ni3N nanosheets as bifunctional electrocatalysts for hydrogen oxidation/evolution reactions

“…An effective method of evaluating the catalytic efficiency of catalysts is to calculate the Tafel slope. 55 Fig. 5c shows the Tafel slopes of different samples.…”

Molecular Engineering Strategies toward Molybdenum Diselenide Design for Energy Storage and Conversion

“… i)SACs are among the most efficient catalysts for numerous catalytic reactions, and 2D MoSe 2 nanosheets can be used as ideal substrates to disperse highly active catalysts. To date, several SACs, including Ni, [ 306 ] Au, [ 78 ] and Ir, [ 105 ] have been applied to couple with MoSe 2 nanosheets to lower the overpotential and improve catalytic activity. The SAC‐decorated MoSe 2 ‐based catalysts exhibited remarkable catalytic properties owing to the synergistic effect of MoSe 2 and SACs.…”

“…[104] The introduction of Ni 0.85 Se promoted the water dissociation reaction, and the number of catalytic active sites of this interfacial structure was higher than those of its individual components, leading to the boosted HER performances in alkaline media. Moreover, MoSe 2 can also synergize with metal selenides or their composites, such as NiCo 2 Se 4 , [88,105] and the electrocatalytic performance of the composites is typically superior to that of MoSe 2 owing to the increased number of catalytic active sites of the composites. In addition to 2D TMDs, perovskite oxides are also applied to couple with MoSe 2 to promote [87] Copyright 2020, Springer Nature.…”