as oxygen reduction reaction (ORR). [2][3][4] In contrast, the DMFCs performed in an alkaline medium exhibit inherent advantages, including: i) improved MOR and ORR kinetics, [5] ii) broad practicality of precious metal-free electrocatalysts, [6] and iii) low cost, [7] and thus have attracted more attention. To enhance the electrochemical performance of DMFCs, enormous attempts have been made earlier on the development of highly efficient MOR electrocatalysts. [8][9][10] So far, the state-of-the-art MOR catalysts are Pt-based materials; [11][12][13][14] however, their large-scale application remains a big challenge, mainly related with the high cost, limited resources, poor stability, and decreasing activity toward poisoning. [15,16] Alternatively, Pd-based materials have emerged as potential replacements of Pt catalysts used in DMFCs for its relatively high abundance, reasonable MOR activity, and stability. [17][18][19] However, the MOR electroactivity of Pd-based materials is still inferior to those of Pt catalysts, which inspires further investigation on advanced Pd-based catalysts with improved activity and durability.Typically, there are two approaches to accomplish this target. One efficient way is nanoengineering of the catalyst to build 3D porous architectures. Such a nanoporous structure not only ensures the efficient utilization of precious Pd with high active surface areas and rich active sites, but also offers fast and efficient transport pathways to enable a favorable reaction kinetics. [20,21] Nevertheless, structure construction alone is not enough, as the single Pd catalysts are vulnerable toward poisoning by MOR intermediate products such as CO. [22] An important strategy for this issue is to combine nanostructured Pd with other supporting materials to improve the intrinsic activity and stability, for instance, transition metals Ni, [23,24] Cu, [20,25] or metal oxides such as Cu 2 O, [26] TiO 2 , [27] and CeO 2 . [28] It was demonstrated that the enhancement was attributed to the bifunctional mechanism and electronic effect, [4,10] that worked together to promote the MOR. These oxophilic metals and more oxygen-rich groups within the catalyst structure can effectively capture OH − species in alkaline media to weaken the adsorption of CO and thus decrease its poisoning on the active sites. [26,29] However, in this regard, the synthesis of Pd-based materials with strong interactions between the highly dispersed Pd and Herein, well-defined Pd nanoparticles (NPs) developed on Ni substrate (Pd NPs/Ni) are synthesized via a facile galvanic replacement reaction (GRR) route performed in ethaline-based deep eutectic solvent (DES). For comparison, a Pd NPs/Ni composite is also prepared by the GRR method conducted in an aqueous solution. The Pd NPs/Ni obtained from the ethaline-DES is catalytically more active and durable for the methanol electro-oxidation reaction (MOR) than those of the counterpart derived from conventional aqueous solution and commercial Pd/C under alkaline media. Detailed kinetic analysi...

Li-ion battery attracts great attentions due to the rapid increasing and urgent demand for high energy storage devices. MAX phase compounds, layered ternary transition metal carbides and/or nitrides, show promise...

No abstract

The rational design and fabrication of highly efficient and durable all-pH catalysts for sustainable electrochemical hydrogen production are of critical importance to building renewable energy systems for the future.

Hydrogen produced by electrochemical water splitting offers a hopeful and renewable solution for addressing the global energy crisis; however, development of highly efficient non-noble-metal electrocatalysts remains a big challenge. Herein, we report a facile strategy to fabricate oxygen deficiencies-rich nickel/nickel (oxy)hydroxide hybrid films as efficient electrocatalysts for water splitting by in situ oxygen evolution reaction (OER) activation. Under OER conditions, the originally deposited Ni films from the ethaline-based deep eutectic solvent (DES) undergo a structural rearrangement with a phase transformation in the oxidation state from Ni(ii) to Ni(iii) at the surface. The change is coupled with an increase in oxygen deficiencies and a pronounced defective precursor is induced by the addition of nitrate ions, providing structural disordering and boosting the intrinsic activity of the catalyst, which strongly enhances the water splitting performance.