Electrocatalytic Water Splitting through the Ni_xS_y Self-Grown Superstructures Obtained via a Wet Chemical Sulfurization Process

Abstract

We report water-splitting application of chemically stable self-grown nickel sulfide (Ni x S y ) electrocatalysts of different nanostructures including rods, flakes, buds, petals, etc., synthesized by a hydrothermal method on a three-dimensional Ni foam (NiF) in the presence of different sulfur-ion precursors, e.g., thioacetamide, sodium thiosulfate, thiourea, and sodium sulfide. The S 2– ions are produced after decomposition from respective sulfur precursors, which, in general, react with oxidized Ni 2+ ions from the NiF at optimized temperatures and pressures, forming the Ni x S y superstructures. These Ni x S y electrocatalysts are initially screened for their structure, morphology, phase purity, porosity, and binding energy by means of various sophisticated instrumentation technologies. The as-obtained Ni x S y electrocatalyst from sodium thiosulfate endows an overpotential of 200 mV. The oxygen evolution overpotential results of Ni x S y electrocatalysts are comparable or superior to those reported previously for other self-grown Ni x S y superstructure morphologies.

Enhanced Oxygen Evolution Reaction with a Ternary Hybrid of Patronite–Carbon Nanotube-Reduced Graphene Oxide: A Synergy between Experiments and Theory

“…Here, the amount of oxygen produced matches well with the theoretical values showing nearly 97.55 ± 2.3% of faradic efficiency (Figure S13). From the literature survey, it has been observed that the metal sulfides develop metal oxides, hydroxides, and oxy-hydroxides on their surface during the OER in an alkaline medium, , whereas some reports have claimed the intactness of the sulfide surface even after the long-term stability test. − In the present investigation, we observe a partial surface transformation from sulfide to oxide/oxo-hydroxide and sulfate and an excellent electrocatalytic performance similar to other metal chalcogenides and phosphide-based OER electrocatalysts. , Here, these oxidized centers are assumed to provide real catalyst sites for the OER process. ,− However, VS x is still responsible for maintaining the electronic conductivity among the oxidized surface and the electrode, facilitating fast charge transport that leads to enhanced electrocatalytic performances. , …”

Recent advances in non‐precious Ni‐based promising catalysts for water splitting application

“…Due to the introduction of Ni 3 B, overpotential was reduced from 320 to 290 mV at 10 mA cm −2 and substantial stability, Ni 3 B/rGO nanocomposite prepared by the simple solution method was a capable electrocatalyst for the OER reaction 101 . Our group obtained NiF 2 from Ni‐foam that documented 172 mV overpotential at 10 mA cm −2 curent density which is less than Ni‐foam in the same solution (242 MV) 102 . Additionally, Ni x S y materials prepared with various shapes by a thermal method on a 3D Ni‐foam at various sulfur ion sources were applied for water splitting application where 200 mV of overpotential for OER was mentioned for sodium thiosulfate precursor 103 …”

“…101 Our group obtained NiF 2 from Ni-foam that documented 172 mV overpotential at 10 mA cm À2 curent density which is less than Nifoam in the same solution (242 MV). 102 Additionally, Ni x S y materials prepared with various shapes by a thermal method on a 3D Ni-foam at various sulfur ion sources were applied for water splitting application where 200 mV of overpotential for OER was mentioned for sodium thiosulfate precursor. 103…”

Recent Advances in Nanoscale Based Electrocatalysts for Metal-Air Battery, Fuel Cell and Water-Splitting Applications: An Overview

“…They are, however, hindered in many applications because of their high cost and scarcity [107]. Researchers have been undertaking several efforts to produce non-precious metal-based water-splitting catalysts, such as sulphides [108], selenides [109], and oxides [110].…”