Enhancing interfacial electron transfer through PANI electron bridge for tailoring dynamic reconstruction and achieving high-performance water oxidation.

Tailoring the dynamic reconstruction of transition metal compounds into highly active oxyhydroxides through surface electron state modification is crucial for advancing water oxidation, yet remains a formidable challenge. In this study, a unique polyaniline (PANI) electron bridge was integrated into the metal-organic frameworks (MOFs)/layer double hydroxides (LDHs) heterojunction to expedite electron transfer from MOFs to LDHs, facilitating electron accumulation at the metal sites within MOF and electron-deficient LDHs. This configuration promotes the surface dynamic reconstruction of LDHs into highly active oxyhydroxides while safeguarding the MOF from corrosion in harsh environments over extended periods. The optimized electronic structure modification of both MOFs and LDHs enhances reaction kinetics. The superior MIL-88B(Fe)@PANI@NiCo LDH catalyst achieved 10 mA∙cm-2 at an overpotential of 202 mV and demonstrated stable operation for 120 h at this current density. This research introduces an innovative approach for guiding electron transfer and dynamic catalyst reconstruction by constructing a PANI electron bridge, potentially paving the way for more efficient catalytic systems.

Suppression of Zinc Dendrite Growth by Enhanced Polyacrylamide Gel Electrolytes in Zinc-ion Battery.

Aqueous zinc-ion batteries have become a promising energy storage battery due to high theoretical specific capacity, abundant zinc resources and low cost. However, zinc dendrite growth and hydrogen evolution reaction limit their application. This study aims to improve the cycling performance and stability of aqueous zinc-ion batteries by improving the gel electrolyte. Polyacrylamide (PAM) is selected as the base material of the gel electrolyte, which has good stability and safety, but the water retention capacity, Zn2+ migration number, and ionic conductivity of PAM are low, which affects the long-term stability of the battery. In response to these problems, we optimized PAM by chemical cross-linking method, and formed an enhanced PAM gel by adding disodium citrate dihydrate (SC). Experimental results show that the introduction of an appropriate amount of SC in the enhanced PAM gel electrolyte can significantly improve its electrochemical performance. The zinc-ion symmetric battery achieved a stable cycle of more than 2100 hours at a current density of 0.5 mA cm-2, which is mainly attributed to the inhibitory effect of the enhanced PAM gel on zinc dendrite growth and hydrogen evolution reaction. This study provides a new direction for the development and application of flexible zinc-ion batteries.

Constructing a Self-Supported Bifunctional Multiphase Heterostructure for Electrocatalytic Overall Water Splitting.

Developing well-performing and stable bifunctional electrocatalysts is of great importance for efficient green hydrogen production through water electrolysis. Herein, a three-dimensional self-supported CoMoS3.13/FeS2/Co3S4 on carbon paper (FeCoMoS/CP) heterostructure with interconnected nanosheets for overall water splitting was fabricated by a facile hydrothermal method followed by vulcanization treatment. The FeCoMoS/CP heterostructure with high structural integrity and more accessible active sites can effectively optimize the electronic structure through component regulation to achieve enhanced catalytic activity. Significantly, the FeCoMoS/CP required overpotentials of 257 mV at 50 mA cm-2 for OER and 280 mV at 20 mA cm-2 for HER. Importantly, the assembled FeCoMoS/CP||FeCoMoS/CP alkaline electrolyzer achieved a superior cell voltage of 1.48 V at 10 mA cm-2 with superb long-term stability, which implies a remarkable electrocatalytic performance of the FeCoMoS/CP heterostructure for overall water splitting. This work provides an applicable route for synthesizing high-performance bifunctional catalysts toward water electrolysis.

"Fence" Effect Enabling a Metal-Organic Framework-Derived Single-Atom Co-N-C Catalyst for High-Performance Zn-Air Batteries.

It offers bright prospects to develop non-Pt group metal (non-PGM) electrocatalysts in the area of energy storage and conversion. Herein, we reported a simple spatial isolation strategy to synthesize Co-based electrocatalysts, using partially substituted Zn atoms in a ZnCo-ZIF precursor. The "fence" effect that originated from the partially substituted Zn atoms can yield a better isolation of Co atoms, achieving selective loading of Co species on nitrogen-doped porous carbon varying from nanoparticles to single atoms. The low boiling point of Zn enables abundant porous structures to the N-doped carbon substrate after pyrolysis. The best performing single-atom Co catalyst (Co-SAs/N-C) exhibits excellent oxygen reduction reaction activity in alkaline media. As an illustration, the rechargeable liquid Zn-air battery incorporating the Co-SAs/N-C catalyst demonstrates a substantial open circuit voltage of 1.49 V, a high specific capacity of 689.3 mAh g-1, and remarkable cycling stability over 200 h. This study paves the way for the strategic development of non-PGM electrocatalysts in battery applications.

Multicomponent Interface and Electronic Structure Engineering in Ir-Doped CoMO4-Co(OH)2 (M = W and Mo) Enable Promoted Oxygen Evolution Reaction.

The core principles of multicomponent interface and electronic structure engineering are essential in designing high-performance catalysts for the oxygen evolution reaction (OER). However, combining these aspects within a catalyst is a significant challenge. In this investigation, a novel approach involving the development of hybrid Ir-doped CoMO4-Co(OH)2 (M = W and Mo) hollow nanoboxes was introduced, enabling remarkably efficient water oxidation electrocatalysis. Constructed from ultrathin nanosheet-assembled hollow nanoboxes, these structures boast a wealth of active centers for intermediate species, which in turn enhance both charge transfer and mass transport capabilities. Moreover, the compelling electronic and synergistic effects arising from the interaction between CoMO4 and Co(OH)2 significantly bolster OER electrocatalysis by facilitating efficient electron transfer. The introduction of Ir atoms serves to strategically adjust the electronic structure, fine-tune its electronic state, and operate as active centers to enhance OER electrocatalysis, thus diminishing the overpotential. This configuration results in Ir-CoWO4-Co(OH)2 and Ir-CoMoO4-Co(OH)2 exhibiting impressively low overpotentials of 252 and 261 mV, respectively, to 10 mA cm-2. Utilized in conjunction with the Pt/C catalyst in a two-electrode system for overall water splitting, a mere 1.53 V cell potential is needed to achieve the desired 10 mA cm-2 current density.

Hierarchical Significance of Environment Impact Factor on the Sand Erosion Performance of Lightweight Alloys.

This paper addresses the challenge of ranking the factors that affect the erosion resistance of lightweight alloys, with a specific focus on aluminum alloys. A three-factor, four-level orthogonal experimental design was employed to examine the influence of various sand particle sizes, erosion speeds, and sand concentrations on the abrasion qualities of these alloys. Parameters such as mass loss, depth, residual stresses, and failure mechanisms were assessed to determine erosion performance. Analysis of variance (ANOVA) and regression analysis of the three key factors were performed. Our findings resulted in an erosion rate formula: erosion rate = 0.679 sand particle size +0.067 sand concentration -0.002 erosion velocity +0.285. Our findings indicate that particle size is the most significant factor affecting erosion rate, with sand concentration and erosion velocity being secondary factors. The failure mechanism reveals that larger sand particles tend to produce deeper slides, and higher sand concentrations result in an increased number of slides. A lower concentration leads to the appearance of erosion pits. And the test conditions of high concentration and low velocity lead to more serious brittle fractures of the substrate, often accompanied by the appearance of cracks.

Promoting ultrasonic cavitation via Negative-Curvature nanoparticles.

It is a challenge to study the nucleation of cavitation bubbles, which critically depends on nanoscale morphological features. Our recent advances in synthesizing colloidal negative-curvature nanoparticles (NGC-NPs) offer a rare opportunity, in comparison to the conventional studies of bulk substrates, where it is difficult to obtain consistent and well-defined surface features. In order to quantitatively assess their effects, we exploit the radical-induced color change of [Fe(SCN)6]3-, which turned out to be a more convenient method than the bending of AgNWs and the fluorescence-based methods. We show that the NGC-NPs outperform positive-curvature nanoparticles (PSC-NPs) and homogeneous nucleation, in terms of promoting cavitation. The NGC-NPs provide a higher percentage of gas-solid interface, and thus reduces the activation barrier during the critical stage of bubble nucleation. This leads a higher probability of cavitation and transforms more energy from ultrasonication to radical formation and shockwaves.

Organic-inorganic hybrid interfaces with π-d electron coupling for preventing metal and sulfur leaching toward enhanced oxygen evolution reaction.

Transition metal sulfides (TMSs) catalysts with high catalytic oxygen evolution reaction (OER) activity have been extensively studied, especially Fe and Co-based sulfides. Fe and Co active sites with a strong synergistic effect, which can adjust the electron density distribution and effectively improve the electrocatalytic OER activity. However, TMSs have poor stability in alkaline environment caused by metal ions and sulfur elements are facilitated to dissolve. In this work, TMSs was modified by polyaniline (PANI) to inhibit the precipitation of iron, cobalt, and sulfur elements and enhance its stability under alkaline conditions. Moreover, π-d structure can also be formed by the coating of PANI, which can further adjust its own electronic structure on the basis of stabilizing the TMSs structure, so as to improve the electrochemical performance, rendering them to stably operate at harsh environment for more than 90 h. These findings offer new guidance for improving the electrocatalytic stability of TMSs.

FeN3S1─OH Single-Atom Sites Anchored on Hollow Porous Carbon for Highly Efficient pH-Universal Oxygen Reduction Reaction.

Regulating the asymmetric active center of a single-atom catalyst to optimize the binding energy is critical but challenging to improve the overall efficiency of the electrocatalysts. Herein, an effective strategy is developed by introducing an axial hydroxyl (OH) group to the Fe─N4 center, simultaneously assisting with the further construction of asymmetric configurations by replacing one N atom with one S atom, forming FeN3S1─OH configuration. This novel structure can optimize the electronic structure and d-band center shift to reduce the reaction energy barrier, thereby promoting oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activities. The optimal catalyst, FeSA-S/N-C (FeN3S1─OH anchored on hollow porous carbon) displays remarkable ORR performance with a half-wave potential of 0.92, 0.78, and 0.64 V versus RHE in 0.1 m KOH, 0.5 m H2SO4, and 0.1 m PBS, respectively. The rechargeable liquid Zn-air batteries (LZABs) equipped with FeSA-S/N-C display a higher power density of 128.35 mW cm-2, long-term operational stability of over 500 h, and outstanding reversibility. More importantly, the corresponding flexible solid-state ZABs (FSZABs@FeSA-S/N-C) display negligible voltage changes at different bending angles during the charging and discharging processes. This work provides a new perspective for the design and optimization of asymmetric configuration for single-atom catalysts applied to the area of energy conversion and storage.

Mixed-valence Cu-based heterostructures for efficient electrochemical nitrate reduction to ammonia.

The electrocatalytic NO3- reduction reaction (NO3RR) to NH3 provides a promising pathway for ambient NH3 synthesis and environmental pollution treatment. Cu and its oxides are recognized as effective NO3RR electrocatalysts due to their favorable d-orbital energy levels and superior kinetics. In this work, mixed-valence Cu-based catalysts with tunable valence states were constructed via an inorganic salt-induced MOF-derived strategy. Notably, optimized Cu-CuxO/C-0.3 featured a Cu/Cu2O heterostructure and demonstrated the lowest Cu valence state. The resulting Cu/Cu2O heterointerface facilitated electron transfer and increased the density of electrochemically active sites, leading to an enhanced faradaic efficiency of 81.4% and a remarkable yield rate of 13.38 mg h-1 cm-2 (ca. 2.39 mol h-1 gcat.-1) at -0.8 V vs. RHE. This work presents insights for designing multi-phase heterostructured NO3RR catalysts and emphasizes their potential significance in efficient ammonia production.

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.

Identification of Immune-Related Genes as Biomarkers for Uremia.

Purpose: Uremia, which is characterized by immunodeficiency, is associated with the deterioration of kidney function. Immune-related genes (IRGs) are crucial for uremia progression. Methods: The co-expression network was constructed to identify key modular genes associated with uremia. IRGs were intersected with differentially expressed genes (DEGs) between uremia and control groups and key modular genes to obtain differentially expressed IRGs (DEIRGs). DEIRGs were subjected to functional enrichment analysis. The protein-protein interaction (PPI) network was constructed. The candidate genes were identified using the cytoHubba tool. The biomarkers were identified using various machine learning algorithms. The diagnostic value of the biomarkers was evaluated using receiver operating characteristic (ROC) analysis. The immune infiltration analysis was implemented. The biological pathways of biomarkers were identified using gene set enrichment analysis and ingenuity pathway analysis. The mRNA expression of biomarkers was validated using blood samples of patients with uremia and healthy subjects with quantitative real-time polymerase chain reaction (qRT-PCR). Results: In total, four biomarkers (PDCD1, NGF, PDGFRB, and ZAP70) were identified by machine learning methods. ROC analysis demonstrated that the area under the curve values of individual biomarkers were > 0.9, indicating good diagnostic power. The nomogram model of biomarkers exhibited good predictive power. The proportions of six immune cells significantly varied between the uremia and control groups. ZAP70 expression was positively correlated with the proportions of resting natural killer (NK) cells, naïve B cells, and regulatory T cells. Functional enrichment analysis revealed that the biomarkers were mainly associated with translational function and neuroactive ligand-receptor interaction. ZAP70 regulated NK cell signaling. The PDCD1 and NGF expression levels determined using qRT-PCR were consistent with those determined using bioinformatics analysis. Conclusion: PDCD1, NGF, PDGFRB, and ZAP70 were identified as biomarkers for uremia, providing a theoretical foundation for uremia diagnosis.

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.

Mechanistic Insights into a Co(II)-Coordinated "Free" Metal Site of 2D Zinc-Based MOFs for ß-Alkylation of Secondary Alcohols with Primary Alcohols.

Through in-depth study of the properties and reaction mechanisms of catalysts, it is possible to better optimize catalytic systems and improve reaction efficiency and selectivity. This remains one of the challenges in the field of catalysis. Therefore, the research and design of catalysts play crucial roles in understanding and optimizing catalytic reaction mechanisms. A robust 2D zinc-based MOFs (Zn-HA) supported Co(II) ion catalyst (Zn-HA@Co) has been designed and synthesized via a coordination-assisted strategy for ß-alkylation of secondary alcohols with primary alcohols. The characterization demonstrated that the anchoring of Co(II) on Zn-HA via coordination could efficiently enhance the Co(II) ion dispersity and interaction between Co(II) and Zn-HA MOFs. Importantly, the density functional theory results have provided mechanistic insights into the energy of the HOMO and LUMO of the Zn-HA@Co catalyst as well as the energy change of the entire process after interacting with the reactants and the specific energy changes of each orbital. The synthesized Zn-HA@Co MOFs effectively lower the energy barrier of the catalytic reaction process. We expect that our research and design of catalysts will serve as valuable guideline for understanding and optimizing catalytic reaction mechanisms.

Evaluation of the deficiency status of 25-hydroxyvitamin D and associated factors in Southwest China: A hospital-based retrospective cross-sectional analysis of a low-latitude, high-altitude, multiracial region.

Vitamin D deficiency is widespread in different populations and regions worldwide and has become a global health issue. The vitamin D status of the population in the Yunnan Province of Southwest China has not been evaluated to date. Therefore, in this study, we evaluated the vitamin D status according to the serum concentrations of 25-hydroxyvitamin D (25(OH)D) in individuals of Yunnan Province, a low-latitude, high-altitude and multiracial region in China. The data on 25(OH)D concentrations from October 2012 to December 2017 were retrospectively collected and assessed using the laboratory information system from 52 950 hospital-based participants (age, 1 day-96 years; females, 73.74%). The serum concentration of 25(OH)D was evaluated using a chemiluminescent immunoassay. The analysis was stratified by sex, age, sampling season, testing year, minority, residential district, latitude, altitude and meteorological factors. Vitamin D status was classified as follows: severe deficiency: <10 ng/mL; deficiency: <20 ng/mL; insufficiency: <30 ng/mL; and sufficiency: ≥30 ng/mL. The results showed that vitamin D deficiency is highly prevalent in Yunnan Province in a hospital-based cohort, with a deficiency and severe deficiency rate of 65.1% and a sufficiency rate of 5.30%. Significantly lower vitamin D levels and sufficiency rates were observed in females than in males (20.13 ± 7.22 ng/mL vs. 17.56 ± 6.66 ng/mL and 8.20% vs. 4.20%; p < 0.01, respectively); in spring and winter (16.93 ± 6.24 ng/mL; 2.97% and 16.38 ± 6.43 ng/mL; 3.06%, respectively) than in summer and autumn (20.23 ± 7.14 ng/mL; 8.02% and 19.10 ± 6.97 ng/mL; 6.61% [p < 0.01], respectively); and in older individuals (0-6 years: 28.29 ± 13.13 ng/mL vs. >60 years: 14.88 ± 8.39 ng/mL; p < 0.01). Relatively higher vitamin D levels were observed in individuals of Yi, Zhuang, Hani, Dai, Miao and Lisu minorities and lower levels in individuals of Hui and Zang minorities compared with those of the Han nationality (p < 0.01). The mean sunlight duration, mean air temperature, maximum ultraviolet value and latitude were significantly correlated with vitamin D levels (r = -0.53, 0.60, 0.31, -0.68, respectively; p < 0.05). These results suggest that vitamin D status is influenced by sex, age, minority, latitude and some meteorological factors in areas with high and low altitudes. Hence, new public health policies, such as advice on sunshine exposure, food fortification and nutrition education, as well as the implementation of vitamin D supplementation programmes must be considered to alleviate vitamin D deficiency in Yunnan province, Southwest China.

Recent progress in structural modification of polymer gel electrolytes for use in solid-state zinc-ion batteries.

Zinc-ion batteries are one of the promising energy storage devices, which have the advantages of environmental friendliness, high safety and low price and are expected to be used in large-scale battery application fields. However, four prominent water-induced adverse reactions, including zinc dendrite formation, zinc corrosion, passivation and the hydrogen evolution reaction in aqueous systems, seriously shorten the cycling life of zinc-ion batteries and greatly hinder their development. Based on this, polymer gel electrolytes have been developed to alleviate these issues due to their unique network structure, which can reduce water activity and suppress water-induced side reactions. Based on the challenges of polymer gel electrolytes, this review systematically summarizes the latest research progress in the use of additives in them and explores new perspectives in response to the existing problems with polymer electrolytes. In order to expand the performance of polymer gel electrolytes in zinc-ion batteries, a range of different types of additives are added via physical/chemical crosslinking, such as organic or inorganic substances, natural plants, etc. In addition, different types of additives and polymerization crosslinking from different angles essentially improve the ionic conductivity of the gel electrolyte, inhibit the growth of zinc dendrites, and reduce hydrogen evolution and oxygen-absorbed corrosion. After these modifications of polymer gel electrolytes, a more stable and superior electrochemical performance of zinc-ion batteries can be obtained, which provides some strategies for solid-state zinc-ion batteries.

3D Hollow Hierarchical Porous Carbon with Fe-N4 -OH Single-Atom Sites for High-Performance Zn-Air Batteries.

The development of innovative and efficient Fe-N-C catalysts is crucial for the widespread application of zinc-air batteries (ZABs), where the inherent oxygen reduction reaction (ORR) activity of Fe single-atom sites needs to be optimized to meet the practical application. Herein, a three-dimensional (3D) hollow hierarchical porous electrocatalyst (ZIF8@FePMPDA-920) rich in asymmetric Fe-N4 -OH moieties as the single atomic sites is reported. The Fe center is in a penta-coordinated geometry with four N atoms and one O atom to form Fe-N4 -OH configuration. Compared to conventional Fe-N4 configuration, this unique structure can weaken the adsorption of intermediates by reducing the electron density of the Fe center for oxygen binding, which decreases the energy barrier of the rate-determining steps (RDS) to accelerate the ORR and oxygen evolution reaction (OER) processes for ZABs. The rechargeable liquid ZABs (LZABs) equipped with ZIF8@FePMPDA-920 display a high power density of 123.11 mW cm-2 and a long cycle life (300 h). The relevant flexible all-solid-state ZABs (FASSZABs) also display outstanding foldability and cyclical stability. This work provides a new perspective for the structural design of single-atom catalysts in the energy conversion and storage areas.

Synergistically engineering of vacancy and doping in thiospinel to boost electrocatalytic oxygen evolution in alkaline water and seawater.

Electronic structure engineering lies at the heart of the catalyst design, however, utilizing one strategy to modify the electronic structure is still challenging to achieve optimal electronic states. Herein, an advanced approach that incorporating both Ru dopants and sulfur vacancies into thiospinel-type FeNi2S4 to synergistically modulate the electronic configuration, is proposed. Deep characterizations and theoretical study reveal that the in-situ formed Ni3+ species are real active centers. Ru doping and sulfur vacancies synergistically tune the electronic states of Ni2+ sites to a near-optimal value, leading to the formation of abundant oxygen evolution reaction (OER)-active Ni3+ species via electrochemical reconstruction. Consequently, the optimized Ru-FeNi2S4 catalyst can exhibit superb electrocatalytic performance towards OER, delivering the overpotentials of 253 mV and 340.8 mV at 10 mA·cm-2 in alkaline water and seawater, respectively. The proper combination of vacancy and heteroatom doping in this work may unlock the catalytic power of conventional catalysts toward electrochemical reactions.

Etched High-Entropy Prussian Blue Analogues as Trifunctional Catalysts for Water, Ethanol, and Urea Electrooxidation.

The introduction of high-entropy and high specific surface area into Prussian blue analogues (PBAs) has yet to create interest in the field of electrocatalytic small-molecule oxidation reactions. Herein, we synthesize a novel class of high-entropy (HE) PBAs with a high specific surface area via a simple NH3·H2O-etching strategy and systematically investigate the electrocatalytic performance of HE-PBA toward electrocatalytic water, ethanol, and urea oxidation reactions. Importantly, the NH3·H2O-etched HE-PBA (denoted as HE-PBA-e) demonstrated enhanced electrocatalytic performance toward small-molecule oxidation compared to the pristine HE-PBA, reaching 10 mA cm-2 with potentials of 1.56, 1.41, and 1.37 V for the oxygen evolution reaction (OER), ethanol oxidation reaction (EOR), and urea oxidation reaction (UOR), respectively. Deep characterizations suggest that the NH3·H2O etching treatment not only creates rich nanopores to enlarge the surface area and boosts the mass transport and electron transfer but also facilitates the formation of high-valence metal oxides to improve the intrinsic activity. This demonstration of how systematically increasing the high oxidation state of metals will serve as a governing principle for the rational design of more advanced HE-PBAs toward the electrooxidation of small molecules.

Engineering defective trimetallic metal-organic framework nanosheets for advanced water oxidation electrocatalysis.

Limited by single metal active sites and low electrical conductivity, designing nickel-based metal-organic framework (MOF) materials with high activity and durability remains a challenge. Here, a novel class of two-dimensional trimetallic MOF nanosheets with plentiful active sites, rich metal defects, and facilitated mass and electron transfer channels is developed as efficient electrocatalysts for boosting oxygen evolution reaction (OER). The unique 2D nanosheet structure enlarges the active area; meanwhile, the organic ligand in the MOF can work as a pillar to enlarge the interplanar space to boost the ion and electron transportation, and the synergistic effect between multi-metal active sites can effectively promote the electrocatalytic activity. Interestingly, after an electrochemical activation process, the optimized NiFeZn MOF nanosheets can yield abundant metal defects, enabling them to deliver a low overpotential of 233 mV at 10 mA cm-2 with a much smaller Tafel slope of 37.8 mV dec-1. More importantly, this method is also universal for the synthesis of the NiFe-MOF family for achieving outstanding electrocatalytic OER performance. These findings present a universal strategy for the construction of a novel class of 2D trimetallic MOF nanosheets for the OER.