Hydrothermal-Induced Cationic Vacancies in NiAl Hydroxide for Enhanced Oxygen Evolution Activities through Optimization of e* Band Broadening.

Nickel-based hydroxides [Ni(OH)] have attracted significant attention as effective oxygen evolution reaction (OER) catalysts. In recent years, defect engineering has been extensively utilized in Ni(OH) modification research. Numerous studies have confirmed that the generation of defects can expose more active sites and regulate electronic states, particularly through the introduction of Al cationic vacancies, which enhance conductivity and thereby improve the catalytic performance.

Promoting Surface Reconstruction in Spinel Oxides via Tetrahedral-Octahedral Phase Boundary Construction for Efficient Oxygen Evolution.

Understanding the origin of surface reconstruction is crucial for developing highly efficient lattice oxygen oxidation mechanism (LOM) based spinel oxides. Traditionally, the reconstruction has been achieved through electrochemical procedures, such as cyclic voltammetry (CV), linear sweep voltammetry (LSV). In this work, we found that the surface reconstruction in LOM-based CoFeAlO catalyst was an irreversible oxygen redox chemical reaction.

Facilitating Formate Selectivity via Optimizing e* Band Broadening in NiMn Hydroxides for Ethylene Glycol Electro-Oxidation.

Ethylene glycol electro-oxidation reaction (EGOR) on nickel-based hydroxides (Ni(OH)) represents a promising strategy for generating value-added chemicals, i.e. formate and glycolate, and coupling water-electrolytic hydrogen production.

Unveiling the Pivotal Role of d Electronic States in Nickel-Based Hydroxide Electrocatalysts for Methanol Oxidation.

The anodic methanol oxidation reaction (MOR) plays a crucial role in coupling with the cathodic hydrogen evolution reaction (HER) and enables the sustainable production of the high-valued formate. Nickel-based hydroxide (Ni(OH)) as MOR electrocatalyst has attracted enormous attention. However, the key factor determining the intrinsic catalytic activity remains unknown, which significantly hinders the further development of Ni(OH) electrocatalyst.

High-spin Co in cobalt oxyhydroxide for efficient water oxidation.

Cobalt oxyhydroxide (CoOOH) is a promising catalytic material for oxygen evolution reaction (OER). In the traditional CoOOH structure, Co exhibits a low-spin state configuration ([Formula: see text]), with electron transfer occurring in face-to-face [Formula: see text] orbitals. In this work, we report the successful synthesis of high-spin state Co CoOOH structure, by introducing coordinatively unsaturated Co atoms.

Key role of e band broadening in nickel-based oxyhydroxides on coupled oxygen evolution mechanism.

A coupled oxygen evolution mechanism (COM) during oxygen evolution reaction (OER) has been reported in nickel oxyhydroxides (NiOOH)-based materials by realizing e band (3d electron states with e symmetry) broadening and light irradiation. However, the link between the e band broadening extent and COM-based OER activities remains unclear. Here, NiFeOOH (x = 0, 0.

Understanding the Origin of Reconstruction in Transition Metal Oxide Oxygen Evolution Reaction Electrocatalysts.

Electrochemical water splitting to generate hydrogen energy fills a gap in the intermittency issues for wind and sunlight power. Transition metal (TM) oxides have attracted significant interest in water oxidation due to their availability and excellent activity. Typically, the transitional metal oxyhydroxides species derived from these metal oxides are often acknowledged as the real catalytic species, due to the irreversible structural reconstruction.

Accelerated Surface Reconstruction through Regulating the Solid-Liquid Interface by Oxyanions in Perovskite Electrocatalysts for Enhanced Oxygen Evolution.

A comprehensive understanding of surface reconstruction was critical to developing high performance lattice oxygen oxidation mechanism (LOM) based perovskite electrocatalysts. Traditionally, the primary determining factor of the surface reconstruction process was believed to be the oxygen vacancy formation energy. Hence, most previous studies focused on optimizing composition to reduce the oxygen vacancy formation energy, which in turn facilitated the surface reconstruction process.

Methods for Characterizing Intercalation in Aqueous Zinc Ion Battery Cathodes: A Review.

Aqueous zinc ion batteries have gained research attention as a safer, economical and more environmentally friendly alternative to lithium-ion batteries. Similar to lithium batteries, intercalation processes play an important role in the charge storage behaviour of aqueous zinc ion batteries, with the pre-intercalation of guest species in the cathode being also employed as a strategy to improve battery performance. In view of this, proving hypothesized mechanisms of intercalation, as well as rigorously characterizing intercalation processes in aqueous zinc ion batteries is crucial to achieve advances in battery performance.

Optimization of Sodium Storage Performance by Structure Engineering in Nickel-Cobalt-Sulfide.

The development of high-performance electrode materials is crucial for the advancement of sodium ion batteries (SIBs), and NiCo S has been identified as a promising anode material due to its high theoretical capacity and abundant redox centers. However, its practical application in SIBs is hampered by issues such as severe volume variations and poor cycle stability. Herein, the Mn-doped NiCo S @graphene nanosheets (GNs) composite electrodes with hollow nanocages were designed using a structure engineering method to relieve the volume expansion and improve the transport kinetics and conductivity of the NiCo S electrode during cycling.

Challenges and Strategies in the Development of Zinc-Ion Batteries.

Although promising, the practical use of zinc-ion batteries (ZIBs) remains plagued with uncontrollable dendrite growth, parasitic side reactions, and the high intercalation energy of divalent Zn ions. Hence, much work has been conducted to alleviate these issues to maximize the energy density and cyclic life of the cell. In this holistic review, the mechanisms and rationale for the stated challenges shall be summarized, followed by the corresponding strategies employed to mitigate them.

Origin of Surface Reconstruction in Lattice Oxygen Oxidation Mechanism Based-Transition Metal Oxides: A Spontaneous Chemical Process.

A fundamental understanding of surface reconstruction process is pivotal to developing highly efficient lattice oxygen oxidation mechanism (LOM) based electrocatalysts. Traditionally, the surface reconstruction in LOM based metal oxides is believed as an irreversible oxygen redox behavior, due to the much slower rate of OH refilling than that of oxygen vacancy formation. Here, we found that the surface reconstruction in LOM based metal oxides is a spontaneous chemical reaction process, instead of an electrochemical reaction process.

Pivotal role of reversible NiO geometric conversion in oxygen evolution.

Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger.

Regulating Dendrite-Free Zn Deposition by a Self-Assembled OH-Terminated SiO Nanosphere Layer toward a Zn Metal Anode.

Zn dendrite growth during repeated plating and stripping of a Zn metal anode often causes short-circuiting by puncturing the separator. Herein, we propose a separator modification strategy to regulate the Zn-ion flux and achieve uniform Zn deposition through the OH-terminated SiO nanosphere coating. The interspaces between the uniform SiO nanospheres construct a network of Zn-ion transport channels, and the negatively charged hydroxyl groups on the surface of SiO nanospheres can electrostatically attract the Zn ions to direct the ion migration.

Understanding of Oxygen Redox in the Oxygen Evolution Reaction.

The electron-transfer process during the oxygen evolution reaction (OER) often either proceeds solely via a metal redox chemistry (adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level). Unlike the AEM, the LOM involves oxygen redox chemistry instead of metal redox, which leads to the formation of a direct oxygen-oxygen (OO) bond. As a result, such a process is able to bypass the rate-determining step, that is, OO bonding, in AEM, which highlights the critical advantage of LOM as compared to the conventional AEM.

Construction of Bio-inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries typically suffer from sluggish interfacial reaction kinetics and drastic cathode dissolution owing to the desolvation process of hydrated Zn and continual adsorption/desorption behavior of water molecules, respectively. To address these obstacles, a bio-inspired approach, which exploits the moderate metabolic energy of cell systems and the amphiphilic nature of plasma membranes, is employed to construct a bio-inspired hydrophobic conductive poly(3,4-ethylenedioxythiophene) film decorating α-MnO cathode. Like plasma membranes, the bio-inspired film can "selectively" boost Zn migration with a lower energy barrier and maintain the integrity of the entire cathode.

Manipulation of Mott-Schottky Ni/CeO Heterojunctions into N-Doped Carbon Nanofibers for High-Efficiency Electrochemical Water Splitting.

Designing affordable and efficient bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has remained a long-lasting target for the progressing hydrogen economy. Utilization of metal/semiconductor interface effect has been lately established as a viable implementation to realize the favorable electrocatalytic performance due to the built-in electric field. Herein, a typical Mott-Schottky electrocatalyst by immobilizing Ni/CeO hetero-nanoparticles onto N-doped carbon nanofibers (abbreviated as Ni/CeO @N-CNFs hereafter) has been developed via a feasible electrospinning-carbonization tactic.

Boosting Aqueous Zn/MnO Batteries via a Synergy of Edge/Defect-Rich Cathode and Dendrite-Free Anode.

Aqueous Zn/MnO batteries exhibit huge potential for grid-scale energy storage but suffer from poor cycling stability derived from both structural instability of cathode and Zn dendrite growth of anode. Here, we report a high-performance aqueous Zn/MnO battery with ZnSO-based electrolyte, comprising a nanoparticle-like cathode with abundant surface oxygen defects (MO-V) and a dendrite-free Zn anode. The transformation from nanowire (α-MnO) to nanoparticle (MO-V) was found by tuning the annealing conditions in an argon flow.

Unraveling MoS and Transition Metal Dichalcogenides as Functional Zinc-Ion Battery Cathode: A Perspective.

The zinc-ion battery (ZIB) is considered as one of the most important alternative battery chemistries to date. However, one of the challenges in ZIB development is the limited selection of materials that can exhibit satisfactory Zn  storage. Transition metal dichalcogenides (TMDs) are widely investigated in energy-related applications due to their distinct physical and chemical properties.

Supramolecular Surface Functionalization of Iron Oxide Nanoparticles with α-Cyclodextrin-Based Cationic Star Polymer for Magnetically-Enhanced Gene Delivery.

Supramolecular polymers formed through host-guest complexation have inspired many interesting developments of functional materials for biological and biomedical applications. Here, we report a novel design of a non-viral gene delivery system composed of a cationic star polymer forming supramolecular complexes with the surface oleyl groups of superparamagnetic iron oxide nanoparticles (SPIONs), for magnetically enhanced delivery of DNA into mammalian cells. The cationic star polymer was synthesized by grafting multiple oligoethylenimine (OEI) chains onto an α-cyclodextrin (α-CD) core.

Atomically Dispersed Mo Sites Anchored on Multichannel Carbon Nanofibers toward Superior Electrocatalytic Hydrogen Evolution.

Developing affordable and efficient electrocatalysts as precious metal alternatives toward the hydrogen evolution reaction (HER) is crucially essential for the substantial progress of sustainable H energy-related technologies. The dual manipulation of coordination chemistry and geometric configuration for single-atom catalysts (SACs) has emerged as a powerful strategy to surmount the thermodynamic and kinetic dilemmas for high-efficiency electrocatalysis. We herein rationally designed N-doped multichannel carbon nanofibers supporting atomically dispersed Mo sites coordinated with C, N, and O triple components (labeled as Mo@NMCNFs hereafter) as a superior HER electrocatalyst.

Dendrite-Free Anodes Enabled by a Composite of a ZnAl Alloy with a Copper Mesh for High-Performing Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) have attracted considerable attention because of their low cost, high intrinsic safety, and high volumetric capacity. However, unexpected dendrite growth and side reactions that arise at the Zn anode can severely hinder the mass adoption of ZIBs in practical applications. Herein, we report a dendrite-free ZIB anode via the hybridization of a eutectic ZnAl alloy with a copper mesh (denoted as ZnAl@Cu-mesh).