Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Abstract

The development of alkaline polymer electrolyte fuel cells and alkaline water electrolysis requires nonprecious metal catalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). Herein, it is reported a phase‐separated Mo–Ni alloy (PS‐MoNi) that is composed of Mo metal and embedded Ni metal nanoparticles. The PS‐MoNi shows excellent hydrogen electrode activity with a high exchange current density (−4.883 mA cm−2), which is comparable to the reported highest value for non‐noble catalysts. Moreover, the amorphous phase‐separated Mo–Ni alloy has better structural and electrochemical stability than the intermetallic compound Mo–Ni alloy (IC‐MoNi). The breakdown potential of PS‐MoNi is as high as 0.32 V, which is much higher than that of reported IC‐MoNi. The X‐ray absorption near edge structure (XANES) and density functional theory (DFT) calculations indicate the electrons transfer from Mo to Ni for PS‐MoNi, leading to suitable adsorption free energies of H* (ΔGH*) on the surface of Mo. This means that the electron density modulation of Mo metal by embedded Ni metal nanoparticles can produce excellent HOR and HER performance.

Recent advances in the pre-oxidation process in electrocatalytic urea oxidation reactions

“…Electrocatalytic energy conversion pathways have received substantial research interest owing to their multiple merits including high energy conversion efficiency, satisfactory reaction selectivity and environmental friendliness. [1][2][3][4][5] For example, fuel cells coupled by the oxygen reduction reaction (ORR) and the electro-oxidation reactions of energy-containing small molecules, such as hydrogen, 6,7 urea, [8][9][10][11] hydrazine, [12][13][14][15] as well as lower alcohols, [16][17][18][19] could efficiently convert the chemical energy to electricity. In another pathway, the electrode coupling between the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) could lead to efficient production of clean hydrogen.…”

Electron Density Modulation of MoO2/Ni to Produce Superior Hydrogen Evolution and Oxidation Activities

“…The synthesis of MoO 2 @CP and Ni@NF has been introduced in our previous work. , In addition, the mass loads of MoO 2 @CP and Ni@NF in this work are ∼0.74 and ∼3.8 mg cm –2 , respectively.…”

“…More importantly, the Ni 2p peak of MoO 2 /Ni shifts to a higher binding energy (Figure a), which proves that the electron density around the Ni atom is reduced. In addition, MoO 2 /Ni exhibits the negative shifted binding energy of Mo 3d (Figure b), which indicates that the electronic structure reconstruction occurred at the MoO 2 /Ni interface. , Therefore, the XPS results show that there is a change in electron density at the MoO 2 /Ni interface.…”

In Situ Grown Co‐Based Interstitial Compounds: Non‐3d Metal and Non‐Metal Dual Modulation Boosts Alkaline and Acidic Hydrogen Electrocatalysis

“…[ 2,12,13 ] Transition metal compounds (TMCs) have received considerable attention as efficient cost‐effective HER electrocatalysts. [ 14–17 ] Among the common TMCs, the transition metal nitrides (TMNs) are metallic in nature, and the presence of nitrogen (N) in TMNs dominates the electronic properties of the metal by increasing the electron densities at the catalyst surface. [ 18–20 ]…”

“…[2,12,13] Transition metal compounds (TMCs) have received considerable attention as efficient cost-effective HER electrocatalysts. [14][15][16][17] Among the common TMCs, the transition metal nitrides (TMNs) are metallic in nature, and the presence of nitrogen (N) in TMNs dominates the electronic properties of the metal by increasing the electron densities at the catalyst surface. [18][19][20] Compared to other TMNs, the HER catalytic properties of cobalt nitrides (such as Co 4 N and Co 5.47 N) have successfully been manipulated via elemental doping and interfacial electronic engineering in alkaline conditions.…”