Cation/Anion Dual-Vacancy Pair Modulated Atomically-Thin Sex -Co3 S4 Nanosheets with Extremely High Water Oxidation Performance in Ultralow-Concentration Alkaline Solutions

Co─Mn Bimetallic Nanowires by Interfacial Modulation with/without Vacancy Filling as Active and Durable Electrocatalysts for Water Splitting

Active and stable nonnoble electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required for water splitting by sustainable electricity. Here, Mn bonded with O and P is incorporated to modulate Co3S4 and Co2P respectively to enhance the catalytic activity and extend the catalyst lifetime. Mn3O4 adjusts the electronic structure of Co3S4 and Co atom fills the oxygen vacancy in Mn3O4. The interfacial interaction endows Co3S4/Mn3O4 to a lower reaction barrier due to ideal binding energies for OER intermediates. Structure stability of active sites and enhanced Co─S bonds by Operando Raman spectroscopy and theoretical calculations reduce the dissolution of Co3S4/Mn3O4, resulting in a lifetime of 500 h at 50 mA cm-2 for OER. The modulation of Co2P by MnP weakens the interaction between Co sites and adsorbed H*, achieving a high activity under a large current for HER. The assembled electrolyzer affords 50 mA cm-2 at 1.58 V and exhibits a lifetime of 350 h at 50 mA cm-2. The calculations disclose the electron interaction for the activity and stability, as well as the enhanced conductivity. The findings develop new avenues toward promoting catalytic activity and stability, making Co─Mn bimetallic nanowires efficient electrocatalysts for nonnoble water electrolyzers.

Vanadium-doped Ni microspheres loaded with phosphatization of NiMoO4 contributing to enhanced electron transfer for stable overall water splitting

At present, there are few reports on the micron-sized catalysts for overall water splitting. In this study, phosphating method were used to construct the self-supporting catalyst (V doped Ni microspheres coated by NiMoO4/Ni12P5) with microspherical structure, providing a short path and a stable structure to guarantee quick electron transfer and excellent catalytic performance. Hence, oxygen evolution reaction (OER) only needs 254 mV to reach a current density of 50 mA cm-2 in 1.0 mol/L KOH, after 114 h without attenuation. The catalyst can achieve a current densitiy of 10 mA cm-2 with a voltage of only 158 mV for hydrogen evolution reaction (HER). When micron scale V-Ni@NiMoO4/Ni12P5 is used as both anode and cathode for overall water splitting, the device can operate at a current density of 10 mA cm-2 for more than 200 h of good stability. Its superior catalytic performance can be attributed to the construction of micron size and phosphating. DFT calculations indicate that the introduction of P better activates the adsorbed *OH and H2O*, reduces reaction the energy barrier, and improves the catalytic activity.

Engineering improved strategies for spinel cathodes in high-performing zinc-ion batteries

The development of high-performing cathode materials for aqueous zinc-ion batteries (ZIBs) is highly important for the future large-scale energy storage. Owing to the distinctive framework structure, diversity of valences, and high electrochemical activity, spinel materials have been widely investigated and used for aqueous ZIBs. However, the stubborn issues of low electrical conductivity and sluggish kinetics plague their smooth applications in aqueous ZIBs, which stimulates the development of effective strategies to address these issues. This review highlights the recent advances of spinel-based cathode materials that include the configuration of aqueous ZIBs and corresponding reaction mechanisms. Subsequently, the classifications of spinel materials and their properties are also discussed. Then, the review mainly summarizes the effective strategies for elevating their electrochemical performance, including their morphology and structure design, defect engineering, heteroatom doping, and coupling with a conductive support. In the final section, several sound prospects in this fervent field are also proposed for future research and applications.

P-doped Co3S4/NiS2 heterostructures embedded in N-doped carbon nanoboxes: Synergistical electronic structure regulation for overall water splitting

Water splitting using transition metal sulfides as electrocatalysts has gained considerable attention in the field of renewable energy. However, their electrocatalytic activity is often hindered by unfavorable free energies of adsorbed hydrogen and oxygen-containing intermediates. Herein, phosphorus (P)-doped Co3S4/NiS2 heterostructures embedded in N-doped carbon nanoboxes were rationally synthesized via a pyrolysis-sulfidation-phosphorization strategy. The hollow structure of the carbon matrix and the nanoparticles contained within it not only result in a high specific surface area, but also protects them from corrosion and acts as a conductive pathway for efficient electron transfer. Density functional theory (DFT) calculations indicate that the introduction of P dopants improves the conductivity of NiS2 and Co3S4, promotes the charge transfer process, and creates new electrocatalytic sites. Additionally, the NiS2-Co3S4 heterojunctions can enhance the adsorption efficiency of hydrogen intermediates (H*) and lower the energy barrier of water splitting via a synergistic effect with P-doping. These characteristics collectively enable the titled catalyst to exhibit excellent electrocatalytic activity for water splitting in alkaline medium, requiring only small overpotentials of 150 and 257 mV to achieve a current density of 10 mA cm-2 for hydrogen and oxygen evolution reactions, respectively. This work sheds light on the design and optimization of efficient electrocatalysts for water splitting, with potential implications for renewable energy production.

Se-doping-induced sulfur vacancy engineering of CuCo2S4 nanosheets for enhanced electrocatalytic overall water splitting

The coordination of the electronic structure and charge transfer through heteroatomic doping and sulfur vacancies is one of the most vital strategies for enhancing the electrocatalytic performance of the oxygen and hydrogen evolution reactions (OER, HER) through water splitting. Se-doped CuCo2S4 nanosheets (CuCo2S3.68Se0.32) with abundant sulfur vacancies were synthesized via a simple hydrothermal method to achieve remarkably efficient electrocatalytic water splitting. Importantly, incorporating Se in three-dimensional nanosheet structures effectively fine-tunes the electronic structure, ensuring ample accessibility of active sites for swift charge carrier transfer and improved reaction kinetics. The optimized CuCo2S3.68Se0.32 offers substantially high electrocatalytic activity with overpotentials of 65 and 230 mV at the current density of 10 mA cm-2 for HER and OER, respectively, which is comparable to commercial catalysts. Combining Se-doping and rich sulfur vacancies facilitates fast charge transport, thus significantly boosting the electrocatalytic activity. Furthermore, utilizing CuCo2S3.68Se0.32 as both the cathode and anode, a two-electrode electrolyser exhibits remarkable performance. It achieves a low voltage of 1.52 V at 10 mA cm-2 and demonstrates exceptional durability over time. This study investigates the significance of doping and vacancies in enhancing electrocatalytic activity for water splitting.

Zeolitic Imidazolate Framework-Derived Zn/Co-S@Ni(OH)2 Nanoarrays with Excellent Energy Storage and Electrocatalytic Performance

The design and development of high-performance electrochemical electrode materials are crucial for energy storage and conversion systems. This work reports a facile preparation of a self-supported Zn/Co-S@Ni(OH)2 array electrode in which a Zn/Co-S nanosheet is derived from a leaf-like zeolitic imidazolate framework (Zn/Co-ZIF-L). The core-shell structure provides multiple benefits such as enhanced electrical conductivity, an abundance of exposed active sites, and strong electronic interactions between Zn/Co-S and ultra-thin Ni(OH)2 nanosheets, facilitating faster charge transfer. Consequently, Zn/Co-S@Ni(OH)2 demonstrates remarkable electrochemical characteristics as an electrode material for supercapacitors with an area capacitance of 12.9 F cm-2 at a current density of 2 mA cm-2 in 2 M KOH. The assembled asymmetric supercapacitor device achieves a high energy density of 0.95 mW h cm-2, while showing excellent longevity with a retention of 90.9% over 5000 cycles. Additionally, the Zn/Co-S@Ni(OH)2 arrays demonstrate significant oxygen evolution reaction activity with an overpotential of 242 mV at 10 mA cm-2 in 1 M KOH and significant stability for more than 100 h. This work provides a valuable approach for synthesizing bifunctional electrode materials for both energy storage and electrocatalysis applications.

Facile, Controllable, and Ultrathin NiFe-LDH In Situ Grown on a Ni Foam by Ultrasonic Self-Etching for Highly Efficient Urine Conversion

As the primary source of nitrogen pollutants in domestic sewage, urine is also an alternative for H₂ production via electrochemical processes. However, it suffers from sluggish kinetics and noble-metal catalyst requirement. Here, we report a non-precious ultrathin NiFe-layered double hydroxide catalyst for the remarkable conversion of urea into N₂ and H₂, which is in situ grown on a Ni foam via ultrasonic self-etching in Fe³⁺/ethylene glycol (EG). EG regulates the etching rate of Fe³⁺, resulting in an ultrathin nanosheet structure with the aid of ultrasonication. This structure dramatically promotes the dehydrogenation process via decreasing the nanolayer thickness from 120 to 3.4 nm and leads to a 4.8-fold increase in the generation of active sites. It exhibits record urea oxidation kinetics (390.8 mA·cm^-2 at 1.5 V vs RHE) with excellent stability (120 h), which is 11.8 times better than that of commercial Pt/C catalyst (33.1 mA·cm^-2). Tests with real urine at 20 mA cm^-2 achieve 74% total nitrogen removal and 2853 μmol·h^-1 of H₂ production. This study provides an attractive landscape for producing H₂ by consuming urine biowastes.

Linnaeite Mineral for NIR Light-Triggered Disruption of Alzheimer's Pore-Forming Aβ Oligomers

Minerals in the Earth's crust have contributed to the natural functioning of ecosystems via biogeochemical interactions. Linnaeite is a cobalt sulfide mineral with a cubic spinel structure that promotes charge transfer reactions with its surroundings. Here we report the hidden feature of linnaeite mineral to dissociate Alzheimer's β-amyloid (Aβ) oligomers under near-infrared (NIR) light irradiation. Alzheimer's disease (AD) is a neurodegenerative disorder caused by the abnormal accumulation of self-assembled Aβ peptides in the elderly brain. The β-sheet structured pore-forming Aβ oligomer (βPFO) is the most neurotoxic species exacerbating the symptoms of AD. However, a therapeutic agent that is capable of inactivating βPFO has not yet been developed. Our microscopic and spectroscopic analysis results have revealed that NIR-excited linnaeite mineral can modulate the structure of βPFO by inducing oxidative modifications. We have verified that linnaeite mineral is biocompatible with and has a mitigating effect on the neurotoxicity of βPFO. This study suggests that minerals in nature have potential as drugs to reduce AD pathology.

Introducing Te for boosting electrocatalytic reactions

The deployment of robust catalysts for electrochemical reactions is a critical topic for energy conversion techniques. Te-based nanomaterials have attracted increasing attention for their application in electrochemical reactions due to their positive influence on the electrocatalytic performance induced by their distinctive electronic and physicochemical properties. Herein, we have summarized the recent progress on Te-based nanocatalysts for electrocatalytic reactions by primarily focusing on the positive influence of Te on electrocatalysts. Firstly, Te-based nanomaterials can serve as an ideal template for the construction of well-defined nanostructures. Secondly, Te doping can significantly modify the electronic structure of the host catalyst, thereby, leading to the optimization of binding strength with intermediates. Furthermore, the Te etching strategy can also create a high density of surface defects, thereby leading to substantial improvement in the electrocatalytic performance. Additionally, many representative Te-based nanocatalysts for electrocatalytic reactions are also summarized and systematically discussed. Finally, a conclusive and perspective discussion is also provided to provide guidance for the future development of more efficient electrocatalysts.