In Situ Electrochemically Formed Ag/NiOOH/Ni₃S₂ Heterostructure Electrocatalysts with Exceptional Performance toward Oxygen Evolution Reaction

Abstract

Developing ultrahigh-activity and ultralong-durability electrocatalysts for oxygen evolution reaction (OER) in alkaline media is of great significance for large-scale alkaline water splitting. Herein, we report a self-supported heterostructure electrocatalyst composed of Ni 3 S 2 nanosheet arrays decorated with Ag nanoparticles grown on nickel foam (Ag/Ni 3 S 2 /NF). Specifically, the insightful studies reveal that the amorphous NiOOH in situ formed on the surface of heterostructure electrocatalyst during OER (NiOOH@Ag/Ni 3 S 2 /NF) is regarded as the real active species. This self-constructed electrode only needs low overpotentials of 183, 195, and 263 mV at the current density of 10, 20, and 100 mA cm −2 , respectively, as well as a low Tafel slope of 37 mV dec −1 in 1 M KOH, and is maintained for 500 h almost without any degradation at a high current density of 100 mA cm −2 . Density functional theory (DFT) calculations reveal that the synergistic effects among multiple components can effectively boost the intrinsic OER activity via increasing conductivity and optimizing binding energy of oxygen-contained intermediates, and the enhanced Ni−O bonding accounts for the superior durability. This work provides deep insight into the key role of Ag on boosting both the catalytic activity and the stability of nickel sulfides toward OER.

Interface engineering and heterometal-doped FeOOH/Ga-Ni3S2nanosheet arrays for efficient electrocatalytic oxygen evolution

“…This result indicates the existence of Ni 3+ sites, which may be attributed to the electrochemical oxidation that occurred during the OER process, forming NiOOH in situ on the surface of Ni 3 S 2 . 62 We conclude that Ni 3 S 2 will partially convert into NiOOH after the OER electrolysis. According to previous studies, 17,60,63 Ni 3 S 2 is prone to forming abundant active nickel oxides in alkaline electrolytes, which optimises the adsorption of oxygenated intermediates and leads to faster rate-determining steps.…”

Activating Lattice Oxygen in High-Entropy LDH for Robust and Durable Water Oxidation

“…XPS results demonstrate a strong electronic coupling between Au single atoms and MnFeCoNiCu LDH. 29 Additionally, we further analyzed the XPS spectra of O 1s (Figure 2a) and identified a peak of 531.0 eV corresponding to oxygen vacancies (VO), which confirms the existence of VO in AuSA-MnFeCoNiCu LDH. This conclusion was further supported by the electron paramagnetic resonance (EPR) test result (Figure S5).…”

“…The HRTEM result (Figure S19) validates the generation of an amorphous layer with a thickness of about 10 nm, which may be an amorphous oxyhydroxides. 10,29 To further identify the amorphous layer, an in situ Raman spectrum test was performed, as illustrated in Figure S20, which confirms the formation of amorphous oxyhydroxides. Moreover, the element mapping analysis (Figure S21) also shows that Mn, Fe, Co, Ni, Cu, O, and Au elements are still uniformly distributed in the catalyst, suggesting the maintenance of the high-entropy structure.…”

Engineering Cu/NiCu LDH Heterostructure Nanosheet Arrays for Highly-Efficient Water Oxidation

“…As shown in Figure 3b, Cu 2.5 /NiCu LDH (86.9 mV dec −1 ) has the lowest Tafel slope compared to the Tafel slopes of NiCu LDH (117.2 mV dec −1 ), Cu 1.25 /NiCu LDH (103.1 mV dec −1 ), and Cu 5 /NiCu LDH (88.1 mV dec −1 ). As shown in Figure 3c, the electrochemically active surface area (ECSA) of the catalyst is determined by measuring the bilayer capacitance (C dl ) due to the positive correlation linear relationship [40]. We used cyclic voltammetry (CV) to calculate the C dl of catalysts in the experiments.…”