Interfacial Engineering of a MoO₂–CeF₃ Heterostructure as a High-Performance Hydrogen Evolution Reaction Catalyst in Both Alkaline and Acidic Solutions

Abstract

Exploring an efficient and pollution-free hydrogen evolution reaction (HER) electrocatalyst based on the combination of rare-earth metal and nonnoble metal is of significant importance. However, successfully achieving such a goal remains highly challenging. Herein, a nanosheet comprising a MoO2–CeF3 heterojunction (MoO2–CeF3/NF) is successfully prepared via a three-step method. (1) Growth of hexahedral nickel hydroxide [Ni­(OH)2] on a 3D nickel foam (NF) as the scaffold. (2) In situ hydrothermal growth of a precursor nanosheet structure on the scaffold. (3) Calcination treatment at 450 °C in the presence of hydrogen. Herein, the electron redistribution at the heterointerface of CeF3 and MoO2 is a contributing factor toward enhanced HER activity. Appropriate introduction of CeF3 can enlarge the size of nanosheets, increase numerous active sites, increase the catalytic durability of the material, and change electron distribution on the MoO2 interface; all of the above improve HER activity. Because of its interfacial nanosheet structure, MoO2–CeF3/NF demonstrates pre-eminent HER capability in both alkaline (1.0 M KOH) and acidic (0.5 M H2SO4) electrolytes, with extremely small overpotentials of 18 and 42 mV at 10 mA cm–2, respectively. This is obviously lower than the overpotential of Pt/C in alkaline media (27 mV), and it is also close to the overpotential of Pt/C in acidic media (41 mV), at the same current density. More importantly, MoO2–CeF3/NF displays a better HER activity than Pt/C at a current density of >112 mA cm–2 in both alkaline and acidic electrolytes. This work offers a novel strategy toward high-performance hydrogen production by designing a transition metal oxide and rare-earth metal heterojunction.

Sacrificial Reagent Free Photocatalytic Oxygen Evolution over CeF3/α‐FeOOH Nanohybrid

“…[18] It is clearly shown that the mixedvalence of Ce 3+ and Ce 4+ exist in CeF 3 /α-FeOOH-400 nanohybrid. The peak of 684.4 eV is attributed to F1s (Figure 3d) [19] All above demonstrate the successful synthesis of CeF 3 /α-FeOOH.…”

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

“…To further demonstrate the increased intrinsic activity of HER, electrochemical impedance spectroscopy tests were performed. The Nyquist plots of these electrode materials and the corresponding results of the equivalent circuit fitting through the dual constant phase element (CPE) model are given in Figure c and Table S1. , In the dual CPE model, solution resistance ( R s ) is the resistance between the working electrode and the reference electrode, R1 and CPE1 are potential-independent and related to surface porosity, while resistance of charge transfer ( R ct ) and CPE2 are potential-dependent and related to HER. − The R ct values of MoO 2 /Ni@NF and Ni@NF were 1.687 and 3.302 Ω, respectively, reflecting that MoO 2 /Ni@NF can exhibit better electron transport in HER …”

Promoting the Phosphidation Process using an Oxygen Vacancy Precursor for Efficient Hydrogen Evolution Reaction

“…Furthermore, to provide an in-depth insight into the intrinsic electrochemical activity of the catalysts, double layer capacitances (C dl ) of these electrocatalysts were calculated based on the CV curves (Figure S5) recorded in a relatively narrow potential window of 0.3-0.7 V (vs. RHE). [29] The electrochemical active surface area (ECSA) could then be estimated from C dl (Figure 3c). Based on the calculation, C dl of FeP/IF was 27.7 mF cm À 2 , which is greater than that of p-FeP/IF (22.7 mF cm À 2 ) and IF (3.1 mF cm À 2 ).…”