Ultrathin NiFeS Nanomeshes with Sulfur Vacancy for Electrocatalytic Hydrogen Evolution

Abstract

The development of novel transition metal‐based electrocatalysts with high hydrogen evolution reaction (HER) activity is significant. NiFeS shows promising potential for HER because of its suitable electronic configuration. However, the low ratio of accessible active sites hinders its HER performance. Processing NiFeS into ultrathin nanosheets with abundant pores and vacancies can increase the number of active sites and enhance the intrinsic activity of active sites, but, the synthesis is still challenging. Here, we developed a facile two‐step conversion strategy to prepare ultrathin NiFeS nanomeshes with sulfur vacancies (NiFeS1‐x UNM). The overpotential of NiFeS1‐x UNM for 10 mA cm−2 was only 81 mV in acid electrolyte, much lower than the counterpart of NiFeS nanosheets (NiFeS NS) without sulfur vacancies (118 mV). Combining the electrochemical characterizations and Density Functional Theory (DFT) calculations, we revealed that the superior performance of NiFeS1‐x UNM originated from the increased active sites, accelerated electron/mass transfer and improved intrinsic activity.

Bio-Inspired FeMo2S4 Microspheres as Bifunctional Electrocatalysts for Boosting Hydrogen Oxidation/Evolution Reactions in Alkaline Solution

“…To investigate the structural defects in FeMo 2 S 4 microspheres, the electron paramagnetic resonance (EPR) spectrum was collected. As shown in Figure f, there is an apparent characteristic signal detected at g = 2.003, which could be assigned to the sulfur vacancies in FeMo 2 S 4 microspheres. − In general, these above results corroborate the successful preparation of bio-inspired FeMo 2 S 4 microspheres, the unique electron structure and abundant structural defects may endow FeMo 2 S 4 with suitable adsorption capacities for the reactants and reaction intermediates in the HOR and HER, thus promoting the electrocatalytic performance.…”

The In Situ Construction of NiFeS on Stainless Steel Mesh as an Efficient Electrocatalyst for UOR

“…Thus, after in situ sulfuration process, the NiFe LDH were converted into a compound containing different kinds of nickel-and iron-based sulphide. 31 Sulfides were generally considered as "pre-catalysts" of UOR due to the high oxidation conditions required for OER reactions in alkaline electrolytes. 32 The hydroxide ions in the electrolyte can easily migrate to the surface of the sulfides and then exchange with the sulfide ions to form metal hydroxides or oxides on the surface.…”

“…88-1710). Thus, after in situ sulfuration process, the NiFe LDH were converted into a compound containing different kinds of nickel-and iron-based sulphide 31. Sulfides were generally considered as "pre-catalysts" of UOR due to the high oxidation conditions required for OER reactions in alkaline electrolytes 32.…”

Solvent-Type Passivation Strategy Controls Solid-State Self-Quenching-Resistant Behavior in Sulfur Dots

“…In this regard, EPR spectroscopy was performed to evaluate the vacancy status of the STPEE-SDs. Analogous EPR signals in the light of sulfur vacancies located at g = 2.003 were monitored, and the defect species would be indicated by vacancy sites or dangling bonds − (Figure ). More significantly, the sulfur vacancy-rich sample (W/STPEE-SDs) exhibited a more intense signal than the vacancy-poor sample (STPEE-SDs).…”