CoFe-Layered Double Hydroxide Coupled with Pd Particles for Electrocatalytic Ethanol Oxidation

Facile Synthesis of High-Entropy Alloy Nanowires for Electrocatalytic Alcohol Oxidation

Considering the structural and compositional advantages of high-entropy alloy (HEA) as high-efficient electrocatalysts, we here present a facile method to prepare high-entropy alloy nanowires with seven elements in an aqueous solution. The as-synthesized PdPtCuAgAuPbCo nanowires possess dispersed one-dimensional morphology and exhibit enhanced electrocatalytic performance with the mass activity of 9.9 A mgPd+Pt -1 toward ethanol electrooxidation. The HEA nanowires also perform superior stability, resistance to CO poisoning, and good electrocatalytic activities toward other alcohols (e. g., ethylene glycol and methanol) oxidation. The synthesis strategy is easy to operate with low cost and has wide application prospects for preparing desired electrocatalysts for fuel cells.

Selective electrooxidation of 5-hydroxymethylfurfural at low working potentials promoted by 3D hierarchical Cu(OH)2@Ni3Co1-layered double hydroxide architecture with oxygen vacancies

Selective electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is of great significance in the manufacture of fine chemicals, liquid fuels, pharmaceuticals, plastics, etc., but still suffers from the high potential input, resulting in high electricity consumption. Developing active, low-cost and stable electrocatalysts is crucial for this electrochemical reaction at low working potentials. Herein, a three-dimensional (3D) hierarchical Cu(OH)2@Ni3Co1-layered double hydroxide architecture with abundant oxygen vacancies (Vo) was synthesized by facile electrodeposition of Ni3Co1-LDH nanosheets on copper foam (CF) supported-Cu(OH)2 nanorods (CF/Cu(OH)2@Ni3Co1-LDH) for the selective electrooxidation of HMF to FDCA. The 3D hierarchical architecture of the Cu(OH)2 nanorod core loaded with Ni3Co1-LDH nanosheet shell facilitates the rapid transfer of charges and exposes more active sites. The synergistic effect of the core-shell nanoarray structure, atomic level dispersion of Ni and Co on LDH laminates, and rich Vo gives 98.12% conversion of HMF, 98.64% yield and 91.71% selectivity for FDCA at a low working potential of 1.0 V vs. RHE. In addition, CF/Cu(OH)2@Ni3Co1-LDH exhibits superior stability by maintaining 93.26% conversion of HMF, 93.65% yield and 91.57% selectivity of FDCA after eight successive cycles, showing the immense potential of utilizing electrochemical conversion for biomass.

Importing Antibonding-Orbital Occupancy through Pd-O-Gd Bridge Promotes Electrocatalytic Oxygen Reduction

The active-site density, intrinsic activity, and durability of Pd-based materials for oxygen reduction reaction (ORR) are critical to their application in industrial energy devices. This work constructs a series of carbon-based rare-earth (RE) oxides (Gd2 O3 , Sm2 O3 , Eu2 O3 , and CeO2 ) by using RE metal-organic frameworks to tune the ORR performance of the Pd sites through the Pd-REx Oy interface interaction. Taking Pd-Gd2 O3 /C as a representative, it is identified that the strong coupling between Pd and Gd2 O3 induces the formation of the Pd-O-Gd bridge, which triggers charge redistribution of Pd and Gd2 O3 . The screened Pd-Gd2 O3 /C exhibits impressive ORR performance with high onset potential (0.986 VRHE ), half-wave potential (0.877 VRHE ), and excellent stability. Similar ORR results are also found for Pd-Sm2 O3 /C, Pd-Eu2 O3 /C, and Pd-CeO2 /C catalysts. Theoretical analyses reveal that the coupling between Pd and Gd2 O3 promotes electron transfer through the Pd-O-Gd bridge, which induces the antibonding-orbital occupancy of Pd-*OH for the optimization of *OH adsorption in the rate-determining step of ORR. The pH-dependent microkinetic modeling shows that Pd-Gd2 O3 is close to the theoretical optimal activity for ORR, outperforming Pt under the same conditions. By its ascendancy in ORR, the Pd-Gd2 O3 /C exhibits superior performance in Zn-air battery as an air cathode, implying its excellent practicability.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.