Oxygen Vacancy‐Enhanced Ternary Nickel‐Tungsten‐Cerium Metal Alloy‐Oxides for Efficient Alkaline Electrochemical Full Cell Water Splitting Using Anion Exchange Membrane

Abstract

Alkaline water electrolysis is an attractive hydrogen generation technology with ultra‐high purity products and zero carbon emissions. However, the sluggish kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both electrodes highly limits their applications. Benefiting from the abundant accessible active sites of the ternary alloy‐oxide structure formed on Ni foam directly, NiCeWOx shows superior HER and OER catalytic performances. The NiCeWOx‐2 (Ce/W ratio with 5/95) displays enhanced OER activity with an overpotential of 263 mV, while the NiCeWOx‐1 (Ce/W ratio with 79.8/21.2) shows better performance for alkaline HER with an overpotential of 130 mV at the current density of 10 mA cm−2. The catalysts show significant enhancement in terms of electrochemical reaction kinetics and conductivity compared to its original NiCeOx and NiWOx alloy phase. The efficient HER‐OER electrocatalytic performance is attributed to its unique alloyed oxygen vacancy structure‐property, which facilitates the diffusion of protons/OH− ions and significantly improves the electron conductivity for catalytic reactions. A low cell potential of 1.65 V is obtained at 10 mA cm−2 for NiCeWOx‐1||NiCeWOx‐2 in a full water‐splitting device in 1 M KOH electrolyzer with an anion exchange membrane. Also, NiCeWOx‐1||NiCeWOx‐2 exhibits extreme high stability after 24 h operation. This novel design utilizes low‐cost and robust electrocatalysts and will be useful for large‐scale alkaline water electrolysis.

Multifunctional CoWO4 2D Array Electrode for Electrocatalytic Overall Water Splitting and Supercapacitor Application

“…The overall water-splitting performance of the CWA//CWA cell is compared with recently reported cobalt and tungsten-based bifunctional catalysts which are used for overall water splitting (Figure d and Table S3). − Figure e,f shows the optical image of overall water splitting of the CWA//CWA cell at 2.75 V potential and reveals that vigorous gas (both H 2 and O 2 ) evolutions were produced and released from the surface of the electrode.…”

Conductive N, S doped Copolymers as Stable Metal-Free Electrocatalysts for Water Splitting

“…Electrical impedance spectroscopy (EIS) spectra and Tafel plots were recorded to study the 4e – OER kinetics of the copolymer electrocatalysts. , These kinetics are moderated by the rate-determining step (Scheme ), which is related to the electrocatalyst used. The obtained Nyquist plots were fitted with the Amstrong–Henderson model circuit (Figure S6); this includes the solution ( R s ) and charge transfer ( R ct ) resistances with a smaller arc radius, which corresponds to the effective transfer of charges with low R ct between the electrolyte and electrode.…”

Biomass Carbon Anchored Co‐N4 Single‐Atom Catalyst for Efficient Hydrogen Evolution, Oxygen Evolution and Alcohol Oxidation Reaction

“…[6][7][8] The scientists found that under alkaline conditions, even the most active Pt-based catalyst, HER/OER/ AOR kinetics is 2 to 3 orders of magnitude slower than that under acidic condition. [9][10][11] Great efforts have been made to develop highly active and stable electrocatalysts in neutral or alkaline conditions, for its importance in large-scale water hydrogen production or alkaline membrane fuel cell industry. [12][13][14] Although Pt-based materials usually possess the best electrochemical catalytic activity, the scarcity and towering cost hamper their widespread application.…”

“…Generally, it is more difficult for most of the electrocatalysts to produce hydrogen or oxygen, even oxidize alcohol in neutral or alkaline conditions, mainly because of the sluggish decomposition kinetics [6–8] . The scientists found that under alkaline conditions, even the most active Pt‐based catalyst, HER/OER/AOR kinetics is 2 to 3 orders of magnitude slower than that under acidic condition [9–11] . Great efforts have been made to develop highly active and stable electrocatalysts in neutral or alkaline conditions, for its importance in large‐scale water hydrogen production or alkaline membrane fuel cell industry [12–14] .…”