Nanostructured Nickel–Cobalt–Titanium Alloy Grown on Titanium Substrate as Efficient Electrocatalyst for Alkaline Water Electrolysis

Abstract

One of the important challenges in alkaline water electrolysis is to utilize a bifunctional catalyst for both hydrogen evolution (HER) and oxygen evolution (OER) reactions to increase the efficiency of water splitting devices for the long durable operations. Herein, nickel-cobalt-titanium (NCT) alloy is directly grown on a high corrosion resistance titanium foil by a simple, single, and rapid electrochemical deposition at room temperature. The electrocatalytic activity of NCT alloy electrodes is evaluated for both HER and OER in aqueous electrolyte. Our NCT electrocatalyst exhibits low overpotentials around 125 and 331 mV for HER and OER, respectively, in 1 M KOH. In addition to this outstanding activity, the bifunctional catalyst also exhibits excellent OER and HER electrode stability up to 150 h of continuous operation with a minimal loss in activity. Further, the NCT alloy directly grown on titanium foil is used to directly construct membrane electrode assembly (MEA) for alkaline electrolyte membrane (AEM) water electrolyzer, which make the practical applicability. This single-step electrodeposition reveals NCT on titanium foil with high activity and excellent electrode stability suitable for replacing alternative commercial viable catalyst for the alkaline water splitting.

Directed Growth of a Bimetallic MOF Membrane and the Derived NiCo Alloy@C/NixCo1‐xO/Ni Foam Composite as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

“…The NiCo@C/Ni x Co 1‐x O/NF catalyst requires a potential of only 1.53 V (i. e., η 100 =300 mV) to attain a current density of 100 mA cm −2 , and this is much lower than that for bare NF at 1.69 V (i. e., η 100 =460 mV), LDH/NF at 1.59 V (i. e., η 100 =360 mV) and its derivative Ni x Co 1‐x O/NF at 1.61 V (i. e., η 100 =380 mV). This indicates the excellent OER activity of NiCo@C/Ni x Co 1‐x O/NF electrode, and this result is better than or comparable to many previously reported NiCo‐based OER catalysts, such as Co@NC/NF (η 10 =390 mV), NiCoP/C (η 10 =330 mV), Co−Ni‐Se/C/NF (η 50 =300 mV), Co x Ni 1‐x @Co y Ni 1‐y O@C (η 10 =570 mV), NiFe LDH (η 100 =300 mV), NiCoFeS/NF (η 100 =160 mV), NiCoTi/Ti foil (η 100 =330 mV), NiCo alloy (η 10 =399 mV) and those noble metal catalysts of RuO 2 (η 10 =380 mV) and IrO 2 (η 10 =380 mV) particles . A detailed comparison has been summarized in Table S1.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…Because of the popularity of the NiO metal oxide in many energy applications, more researches should be carried out to synthesize and characterize the polyoxonickelates that combine the virtues of nickel oxide and molecular design flexibility. Nevertheless, nickel species are found to be common ingredient in many polyoxometalates for cluster functionalization . For example, polynuclear nickel clusters with Ni 12 , Ni 13 , and Ni 25 cores has been incorporated in polyoxometalate to act as water oxidation catalysts whereas the photocatalysis of Ni 2+ and NiO is ruled out .…”

“…Nevertheless, nickel species are found to be common ingredient in many polyoxometalates for cluster functionalization. 60,[150][151][152][153][154][155][156][157][158][159][160] For example, polynuclear nickel clusters with Ni 12 , Ni 13 , and Ni 25 cores has been incorporated in polyoxometalate to act as water oxidation catalysts whereas the photocatalysis of Ni 2+ and NiO is ruled out. 60 Ni 24 cages with calixarene and Pt clusters have been employed to activate the hydrogen evolution reaction.…”

CuCo2S4Deposited on TiO2: Controlling the pH Value Boosts Photocatalytic Hydrogen Evolution

“…Temperature dependent Nyquist plots (see Supporting Information Figure S19 and given fitting details) show a typical shape of frequency-dependent resistivity similar to comparable materials. [85,86] At 30°C, the temperature used for photocatalytic experiments, the estimated materials conductivity amounts to ca. Figure S19) allows an estimation of the activation energy E a necessary for obtaining electrical conductivity in the material, being 0.42 eV (41 kJ/mol).…”