Effect of Graphene Encapsulation of NiMo Alloys on Oxygen Evolution Reaction

Abstract

Electrochemical water splitting is an ecofriendly technology for generating oxygen and hydrogen from water. The electrode is a key component that controls the efficiency of water splitting. Although noble metals such as Pt, Ru and Ir can achieve high energy efficiencies, their application in water splitting is limited by their high cost. Thus, developing efficient noble-metal-free electrodes is necessary to achieve sustainable hydrogen societies. Here, we report a technique of graphene encapsulation of NiMo alloys for realizing both high catalytic activity and high chemical stability in non-noble metal anodes in transition metal impurities-free aqueous KOH electrolyte. Electrochemical analysis showed that graphene encapsulation significantly enhanced the oxygen evolution reaction (OER) activities of the NiMo anodes and provided long electrode lifetimes and performances comparable to those of commercially available anodes. Density functional theory calculation revealed that graphene encapsulation significantly reduced the adsorption energy of intermediates onto the NiMo surface, thereby remarkably enhancing the OER activity. The graphene encapsulation method provides a promising electrode design to improve the performance in water splitting electrolyzers.

A comprehensive study of indole catalytic hydrodenitrogenation under hydrothermal conditions

“…Oxidation of Ni may have occurred in the near‐surface region during synthesis and/or XPS sample preparation. However, after the reaction, as shown in Figure 14B, no zero‐valent signal of Ni 2p was detected, whereas the peak at 853.9 eV with satellite peak at 860.5 eV, corresponding to Ni 2+ 2p 3/2 , 39 and another peak at a BE of 856.3 eV also indicate the presence of nickel oxide 40 . Moreover, as shown in Figure 14C, the BE peak of overall Ni 2p at 852.8 eV in the fresh catalyst shifted toward higher BE of 856.2 eV in the used catalyst, indicating a more oxidized Ni after the hydrothermal reaction.…”

“…As shown in Figure 14A, three peaks of Ni 2p of the fresh catalyst can be deconvoluted by a Gaussian peak‐fitting method. The peak at a binding energy (BE) of 852.8 eV with its satellite peak at 857.4 eV corresponds to Ni ° 2p 3/2 38 and a small peak at 860.5. eV corresponds to Ni 2+ 2p 3/2 39 . Oxidation of Ni may have occurred in the near‐surface region during synthesis and/or XPS sample preparation.…”

Recent Advances in Amino‐Based Molecules Assisted Control of Noble‐Metal Electrocatalysts

“…The appropriate carbon substrate improves the electrocatalytic performance and stability of catalysts by efficient synergistic effects between catalysts and substrates. [ 161–164 ] Benefitting from the structural and compositional advantages, the PtCu‐nanowires/rGO exhibits enhanced ORR activity with superior onset potential (1.094 V) and half‐wavy potential (0.895 V) and robust electrocatalytic stability.…”

Defect Engineering of Sb2Te3 through Different Doses of Ion Irradiation to Boost Hydrogen Evolution Reaction Performance

“…In the past few years, a large number of non-noble-metal catalysts have been developed. For example, various transition metals (Fe, Ni, Mo, and W) and their compounds (Ni–Mo alloy, , MoS 2 , , WxC, WS 2 , and FeS 2 ) have been proven to have high HER activity.…”