Iridium Single Atoms Coupling with Oxygen Vacancies Boosts Oxygen Evolution Reaction in Acid Media

Abstract

Simultaneous realization of improved activity, enhanced stability, and reduced cost remains a desirable yet challenging goal in the search of electrocatalysis oxygen evolution reaction (OER) in acid. Herein, we report a novel strategy to prepare iridium single-atoms (Ir-SAs) on ultrathin NiCo2O4 porous nanosheets (Ir–NiCo2O4 NSs) by the co-electrodeposition method. The surface-exposed Ir-SAs couplings with oxygen vacancies (VO) exhibit boosting the catalysts OER activity and stability in acid media. They display superior OER performance with an ultralow overpotential of 240 mV at j = 10 mA cm–2 and long-term stability of 70 h in acid media. The TOFs of 1.13 and 6.70 s–1 at an overpotential of 300 and 370 mV also confirm their remarkable performance. Density functional theory (DFT) calculations reveal that the prominent OER performance arises from the surface electronic exchange-and-transfer activities contributed by atomic Ir incorporation on the intrinsic VO existed NiCo2O4 surface. The atomic Ir sites substantially elevate the electronic activity of surface lower coordinated Co sites nearby VO, which facilitate the surface electronic exchange-and-transfer capabilities. With this trend, the preferred H2O activation and stabilized *O have been reached toward competitively lower overpotential. This is a generalized key for optimally boosting OER performance.

Plasmon‐Enhanced Charge Separation and Surface Reactions Based on Ag‐Loaded Transition‐Metal Hydroxide for Photoelectrochemical Water Oxidation

“…As such, the traditional OER model was investigated using a standard three-electrode system. [34][35][36][37] Co(OH) 2 and Co(OH) x -Ag electrodes were tested for comparison (Figures S27 and S28, Supporting Information). Figure 5a exhibits the linear sweep voltammetry (LSV) curves with iR compensation of all samples.…”

Tailoring Water Dissociation Energy by Platinum Single-Atom Catalyst Coupled with Transition Metal/metal Oxide Heterostructure for Accelerating Alkaline Hydrogen Evolution Reaction

“…Therefore, the Pt-site could play a protecting role for stabilizing the Ni valence state and a distributary role by binding OH and H species to low the deactivation of absorption sites in case of over-binding of intermediates on the active sites for NiO/Ni heterostructure coupled single-atom Pt. 53 Based on the above finding, we further explore the reaction barrier of the fabricated catalysts for H2O splitting in alkaline conditions, consisting of the dissociation of H2O molecule of Volmer step and the subsequent conversion of H to H2, which mainly depends on how OH and H bond to the active sites on the surface of the catalysts. 54 We found that both H and OH bind weakly to the pure NiO surface.…”

Electrocatalysis for the Oxygen Evolution Reaction in Acidic Media: Progress and Challenges

“…One solution to this conundrum is to develop suitable catalysts with high efficiency and low overpotential [27]. However, most of the excellent OER catalysts with high activity and durability are not stable in acidic solutions [28]. They are easily oxidized and decomposed in a strong acid system, which is one of the indispensable working conditions for PEMWE [29].…”

“…In order to maximize the utilization of each active site (approaching 100%) as well as shed light on the effect of the structure of active centers and ligating atoms on the OER activity, catalysts have thus been continuously downsized to the single-atom (SA) level. Single-atom catalysts (SACs) have emerged as a hot new branch of heterogeneous catalysts due to their excellent catalytic performance and financial benefits [28]. Owing to the high requirements for the dispersion, activity, and stability of the atoms, an appropriate support must be selected to optimize the physiochemical properties of the metal atoms anchored [81].…”

“…The unique coordination configuration of the dispersed metal atoms and coordinating atoms together create active sites for OER catalysts; therefore, the coordination−activity relationship has a strong impact on the catalytic performance [92]. In fact, targeted synthesis of precious metal single-atom-based OER electrocatalysts remains a bottleneck and has been pursued in the search for better OER catalysis, especially under acid conditions [28]. Generally, carbon supports often suffer severe corrosion problems under acid conditions and oxide supports are not always conductive, which brings about huge trouble for the design of single-atom catalysts [93].…”