Rationally Constructing Chalcogenide–Hydroxide Heterostructures with Amendment of Electronic Structure for Overall Water-Splitting Reaction

Abstract

Rational design and fabrication of electrocatalysts with outstanding performances and long-term durabilities are highly challenging for overall water-splitting reactions. Herein, interfacially engineered CoS@NiV-LDH heterostructures are fabricated by a simple top-down approach and used as bifunctional electrocatalysts for overall water splitting. Experimental results proved that the creation of an interface between pristine CoS and NiV-LDH can optimize the electronic structure of the active sites by transferring electrons from the NiV-LDH site to CoS, which boosts the formation of the NiOOH active phase, enhancing the catalytic performance in a 1 M KOH solution. While coupled with the heterostructure CoS@NiV-LDH as the anode and cathode, it demands a cell voltage of just 1.57 V to attain a current density of 10 mA cm–2 with remarkable stability for 70 h. Density functional theory (DFT) calculations reveal improved catalytic activity toward the oxygen evolution reaction (OER) for CoS@NiV-LDH with a lower energy barrier originating from the charge transfer-induced synergistic mechanism at the CoS and NiV-LDH interface. Moreover, the observed downshift of the d-band center for the CoS@NiV-LDH heterostructure explains their enhanced performance toward the hydrogen evolution reaction (HER), facilitating the H* adsorption/desorption process.

Atmospheric-Water-Induced Reversible Structural Transformation of a Two-Dimensional Ni(II)-Based Ferromagnetic MOF: A Highly Efficient Water Oxidation Electrocatalyst and Colorimetric Water Sensor

“…The overpotential (η) calculation is based on the equation η = E RHE − 1.23 V. 66 The Tafel slope was estimated from the fitting of the overpotential versus log j following the Tafel equation η = b log(j/j 0 ), where b corresponds to the expected slope, j 0 designates the exchange current density, and j is the current density. 67 The electrochemically active surface areas (ECSA) are generally calculated utilizing electrochemical double-layer capacitance (C dl ) as shown: 68,69…”

“…The overpotential (η) calculation is based on the equation η = E RHE – 1.23 V . The Tafel slope was estimated from the fitting of the overpotential versus log j following the Tafel equation η = b log( j / j 0 ), where b corresponds to the expected slope, j 0 designates the exchange current density, and j is the current density . The electrochemically active surface areas (ECSA) are generally calculated utilizing electrochemical double-layer capacitance ( C dl ) as shown: , italici normalc = ν × italicC normald normall normalE normalC normalS normalA = C normald normall C normals × m Here i c denotes the double-layer charging current (at non-Faradaic potential) ensuing from scan-rate (ν)-dependent CVs, C s signifies the specific capacitance value of 0.040 mF/cm 2 found from the values described in the literature, and m is the loaded mass of the material on the GC electrode (0.021 mg).…”

Morphology Modulation and Phase Transformation of Manganese–Cobalt Carbonate Hydroxide Caused by Fluoride Doping and Its Effect on Boosting the Overall Water Electrolysis

“…The elemental mapping and energy-dispersive X-ray spectrometry (EDX) were recorded on FE-SEM. High-resolution transmission electron microscopy (HRTEM) was performed to investigate the catalyst structure with a Tecani G F20. The X-ray diffraction (XRD) test was utilized for the phase analysis of the samples in the 2θ range from 10 to 80° with the GBCMMA instrument and Cu Kα radiation (λ = 1.5406 Å).…”

“…The problem of global warming and depletion of petroleum resources has increased the demand to investigate and develop clean, renewable, and sustainable energy conversion and regenerative energy sources . Among various candidate devices, water electrolysis is an effective approach and a green route with high efficiency and low cost for energy storage and conversion, which can split water into clean hydrogen fuel from aqueous solutions with zero carbon content and often deemed as a promising energy carrier without emitting any greenhouse gases. − The electrochemical water splitting process includes two half-reactions that generates hydrogen on the cathode and oxygen on the anode with water as its feedstock and can be considered as an abundant and renewable hydrogen source. − However, the practical applications of the water splitting process suffer from some inherent limitations, including the sluggish kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction are strongly uphill with large overpotentials that hinder the practical applications of water splitting. , The sluggish kinetics of OER and HER in the water splitting process is due to the multistep proton transfer and electron transfer to release both H 2 and O 2 by breaking the O–H bond and forming O–O and/or H–H together.…”

Construction of Ultrathin Cobalt-Based Nanosheet Arrays on Titanium Mesh as Asymmetric Electrodes for Overall Water Splitting

“…It is well known that using strong acid or strong base as the electrolyte for hydrogen production can greatly reduce the overpotential of the reaction process, and using bifunctional electrocatalysts as the cathode and anode can simplify the composition of the electrolytic cell. − The corrosion problem of electrocatalysts in acidic electrolytes cannot be ignored under long-term high current density working conditions, so alkaline water splitting has been gradually applied in the commercial production of hydrogen. − However, the working current density of alkaline electrolyzed water is about 0.25 A cm –2 , and the energy efficiency is usually around 60%. Therefore, the development of catalysts with high current density, good stability, and strong corrosion resistance is the key to the application in the industrial field.…”