Sub-2 nm mixed metal oxide for electrochemical reduction of carbon dioxide to carbon monoxide

Mixed metal oxide(MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components:reduced metal and its metal oxide counterpart during an electrocatalytic reaction.Here,a synthetic method utilizing a MOF-derived micro/mesoporous carbon as a template to prepare sub-2 nm MMO catalysts for CO_(2) electro reduction is reported.Starting from the zeolite imidazolate framework(ZIF-8),the pyrolyzed derivatives were used to synthesize sub-2 nm Pd-Ni MMO with different compositions.The Ni-rich(Pd_(20)-Ni_(80)/ZC) catalyst exhibits unexpectedly superior performance for CO production with an improved Faradaic efficiency(FE) of 95.3% at the current density of 200 mA cm^(-2) at-0.56 V vs.reversible hydrogen electrode(RHE) compared to other Pd-Ni compositions.X-ray photoelectron spectroscopy(XPS) analysis confirms the presence of Ni^(2+) and Pd^(2+) in all compositions,demonstrating the presence of MMO.Density functional theory(DFT) calculation reveals that the lower CO binding energy on the surface of the Pd_(20)-Ni_(80) cluster eases CO desorption,thus increasing its production.This work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface.

Biomimetic Fe_(7)S_(8)/Carbon electrocatalyst from[FeFe]-Hydrogenase for improving pH-Universal electrocatalytic hydrogen production Special Collection:Aggregation-Induced Processes and Functions

Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen production.Inspired by biological systems,Fe_(7)S_(8)nanoparticles incorporated on polydopamine matrix electrocatalyst were synthesized by co-precipitation and annealing process.The resulting Fe_(7)S_(8)/C electrocatalyst possesses a three-dimensional structure and exhibits enhanced electrocatalytic performance for hydrogen production across various pH conditions.Notably,the Fe_(7)S_(8)/C electrocatalyst demonstrates exceptional activity,achieving low overpotentials of 90.6,45.9,and 107.4 mV in acidic,neutral,and alkaline environments,respectively.Electrochemical impedance spectroscopy reveals that Fe_(7)S_(8)/C exhibits the lowest charge transfer resistance under neutral conditions,indicating an improved proton-coupled electron transfer process.Continuous-wave electron paramagnetic resonance results confirm a change in the valence state of Fe from 3+to 1+during the hydrogen evolution reaction(HER).These findings closely resemble the behavior of natural[FeFe]-hydrogenase,known for its superior hydrogen production in neutral conditions.The remarkable performance of our Fe_(7)S_(8)/C electrocatalyst opens up new possibilities for utilizing bioinspired materials as catalysts for the HER.

Heteroepitaxial growth of ZnO nanosheet bands on ZnCo204 submicron rods toward high-performance Li ion battery electrodes

We report the direct synthesis of ZnC0204 and ZnO/ZnC0204 submicron rod arrays grown on Ni foil current collectors via an ammonia-evaporation-induced method by controlling the ratio of Zn to Co. These three-dimensional （3D） hierar- chical self-supported nanostructures are composed of one-dimensional （1D） ZnCo204 rods and two-dimensional （2D） ZnO nanosheet bands perpendicular to the axis of the each ZnCo204 rod. We carefully deal with the heteroepitaxial growth mechanisms of hexagonal ZnO nanosheets from a crystallographic point of view. Furthermore, we demonstrate the ability of these high-surface-area ZnO/ZnCo204 heterostructured rods to enable improved electrolyte permeability and Li ion transfer, thereby enhancing their Li storage capability （-900 mA.h.g-1 at a rate of 45 mA.h.g-1） for Li ion battery electrodes.