Tensile nanostructured hierarchically porous non-precious transition metal-based electrocatalyst for durable anion exchange membrane-based water electrolysis

Electrochemical water electrolysis is a promising method for sustainable hydrogen production while transiting towards hydrogen economy. Among many, the Anion Exchange Membrane (AEM) based water electrolyzer is an emerging yet potentially affordable technology on maturity for producing large-scale hydrogen accommodating the usage of Non-Platinum Group Metal (non-PGM) based inexpensive electrocatalysts. Herein, we demonstrate the excellent performance of a bifunctional Nickel Copper Phosphide-Nickel sulphide (NCP-NS) electrocatalyst with a unique tensile nanostructure obtained via a facile, controlled ambient galvanic displacement route. An AEM electrolyzer with a larger active area of 10 cm2 stacked with the symmetric NCP-NS electrodes and a membrane demonstrates scalability with a requirement of a mere 1.66 V to reach a current density of 10 mA cm-2. The nickel-copper phosphide boosts the kinetics of charge transfer between the electrode and electrolyte interface, while a unique combination of a few nickel sulphide phases present in the catalyst provides sufficiently appropriate active sites for the overall water electrolysis. For the first time, we report a room temperature performance of ∼ 230 mA cm-2 at 2 V for a non-PGM-based bifunctional electrocatalyst with exceptional durability for over 300 h of operation in an AEM water electrolyser with a retention rate of 95 %-97 % at a current density range of 80-800 mA cm-2.

Ultrathin and Porous 2D PtPdCu Nanoalloys as High-Performance Multifunctional Electrocatalysts for Various Alcohol Oxidation Reactions

We precisely synthesized two-dimensional (2D) PtPdCu nanostructures with the morphology varying from porous circular nanodisks (CNDs) and triangular nanoplates (TNPs) to triangular nanoboomerangs (TNBs) by tuning the molar ratios of metal precursors. The PtPdCu trimetallic nanoalloys exhibit superior electrocatalytic performances to alcohol oxidation reactions due to their unique structural features and the synergistic effect. Impressively, PtPdCu TNBs exhibit a high mass activity of 3.42 mg_Pt+Pd^-1 and 1.06 A·mg_Pt^-1 for ethanol and methanol oxidation compared to PtPd, PtCu, and pure Pt, which is 3.93 and 4.07 times that of commercial Pt/C catalysts, respectively. Moreover, 2D PtPdCu TNPs and PtPdCu CNDs also show a highly improved electrocatalytic activity. Furthermore, as all-in-one electrocatalysts, PtPdCu nanoalloys display excellent electrocatalytic activity and stability toward the oxidation of other alcohol molecules, such as isopropyl alcohol, glycerol, and ethylene glycol. The enhanced mechanism was well proposed to be the abundant active sites and upshifted d-band center based on density functional theory calculations.

Boosting Hydrogen Evolution through the Interface Effects of Amorphous NiMoO4-MoO2 and Crystalline Cu

The rational design and synthesis of a highly efficient and cost-effective electrocatalyst for hydrogen evolution reaction (HER) are of great importance for the efficient generation of sustainable energy. Herein, amorphous/crystalline heterophase Ni-Mo-O/Cu (denoted as a/c Ni-Mo-O/Cu) was synthesized by a one-pot electrodeposition method. Thanks to the introduction of metallic Cu and the formation of amorphous Ni-Mo-O, the prepared electrocatalyst exhibits favorable conductivity and abundant active sites, which are favorable to the HER progress. Moreover, the interfaces consisting of Cu and Ni-Mo-O show electron transfers between these components, which might modify the absorption/desorption energy of H atoms, thus accelerating HER activity. As expected, the prepared a/c Ni-Mo-O/Cu possesses excellent HER performance, which affords an ultralow overpotential of 34.8 mV at 10 mA cm^-2, comparable to that of 20 wt % Pt/C (35.0 mV), and remarkable stability under alkaline conditions.