Anchored Cobalt Nanoparticles on Layered Perovskites for Rapid Peroxymonosulfate Activation in Antibiotic Degradation.

In the Fenton-like reaction, revealing the dynamic evolution of the active sites is crucial to achieve the activity improvement and stability of the catalyst. This study reports a perovskite oxide in which atomic (Co0) in situ embedded exsolution occurs during the high-temperature phase transition. This unique anchoring strategy significantly improves the Co3+/Co2+ cycling efficiency at the interface and inhibits metal leaching during peroxymonosulfate (PMS) activation. The Co@L-PBMC catalyst exhibits superior PMS activation ability and could achieve 99% degradation of tetracycline within 5 min. The combination of experimental characterization and density functional theory (DFT) calculations elucidates that the electron-deficient oxygen vacancy accepts an electron from the Co 3d-orbital, resulting in a significant electron delocalization of the Co site, thereby facilitating the adsorption of the *HSO5/*OH intermediate onto the "metal-VO bridge" structure. This work provides insights into the PMS activation mechanism at the atomic level, which will guide the rational design of next-generation catalysts for environmental remediation.

Recent Advances in Iridium-based Electrocatalysts for Acidic Electrolyte Oxidation.

Ongoing research to develop advanced electrocatalysts for the oxygen evolution reaction (OER) is needed to address demand for efficient energy conversion and carbon-free energy sources. In the OER process, acidic electrolytes have higher proton concentration and faster response than alkaline ones, but their harsh strongly acidic environment requires catalysts with greater corrosion and oxidation resistance. At present, iridium oxide (IrO2) with its strong stability and excellent catalytic performance is the catalyst of choice for the anode side of commercial PEM electrolysis cells. However, the scarcity and high cost of iridium (Ir) and the unsatisfactory activity of IrO2 hinder industrial scale application and the sustainable development of acidic OER catalytic technology. This highlights the importance of further research on acidic Ir-based OER catalysts. In this review, recent advances in Ir-based acidic OER electrocatalysts are summarized, including fundamental understanding of the acidic OER mechanism, recent insights into the stability of acidic OER catalysts, highly efficient Ir-based electrocatalysts, and common strategies for optimizing Ir-based catalysts. The future challenges and prospects of developing highly effective Ir-based catalysts are also discussed.

Accelerated deprotonation with a hydroxy-silicon alkali solid for rechargeable zinc-air batteries.

Transition metal oxides are promising electrocatalysts for zinc-air batteries, yet surface reconstruction caused by the adsorbate evolution mechanism, which induces zinc-ion battery behavior in the oxygen evolution reaction, leads to poor cycling performance. In this study, we propose a lattice oxygen mechanism involving proton acceptors to overcome the poor performance of the battery in the OER process. We introduce a stable solid base, hydroxy BaCaSiO4, onto the surfaces of PrBa0.5Ca0.5Co2O5+δ perovskite nanofibers with a one-step exsolution strategy. The HO-Si sites on the hydroxy BaCaSiO4 significantly accelerate proton transfer from the OH* adsorbed on PrBa0.5Ca0.5Co2O5+δ during the OER process. As a proof of concept, a rechargeable zinc-air battery assembled with this composite electrocatalyst is stable in an alkaline environment for over 150 hours at 5 mA cm-2 during galvanostatic charge/discharge tests. Our findings open new avenues for designing efficient OER electrocatalysts for rechargeable zinc-air batteries.

Highly Reversibly Stretchable and Elastically Wearable Textile Supercapacitor.

Rapid and full recovery is the major challenge for the commercialization and further growth of textile-based wearable supercapacitors. Herein, reversibly stretchable and rapidly reboundable textile supercapacitors (TSCs) are developed via the utilization of NiCu2Se3/Cu-Ni alloy-plated cotton cloth (CNAPCC) textile as the cathode and Fe2CuSe3/CNAPCC textile as the anode. Both NiCu2Se3/CNAPCC and Fe2CuSe3/CNAPCC are obtained by a simple in situ oxidation reaction, followed by an ion exchange strategy. Meanwhile, a stable double-network (DN) structure is constructed, covering the knitted cotton cloth (KCC) and Cu-Ni alloy-plated layer (CNAPL). The DN textile structure significantly endows the NiCu2Se3/CNAPCC stretchable electrode with superior mechanical properties, exhibiting high elongation at a break of 470% with a stress of 7.19 MPa and full recovery after 100% strain with almost no residual deformation left after merely 0.2 s. Moreover, the assembled TSC provides a large energy density of 82 Wh kg-1 at a power density of 750 W kg-1. Besides, 50,000 charge/discharge cycle tests under static stretching are performed. The supercapacitor exhibits rapid recovery and excellent cycling stability of 92.2% capacitance retention under different strains (from 0 to 200%).

Copper-Based Catalysts for Electrochemical Reduction of Carbon Dioxide to Ethylene.

Electrochemical reduction of CO2 into high energy density multi-carbon chemicals or fuels (e. g., ethylene) via new renewable energy storage has extraordinary implications for carbon neutrality. Copper (Cu)-based catalysts have been recognized as the most promising catalysts for the electrochemical reduction of CO2 to ethylene (C2 H4 ) due to their moderate CO adsorption energy and moderate hydrogen precipitation potential. However, the poor selectivity, low current density and high overpotential of the CO2 RR into C2 H4 greatly limit its industrial applications. Meanwhile, the complex reaction mechanism is still unclear, which leads to blindness in the design of catalysts. Herein, we systematically summarized the latest research, proposed possible conversion mechanisms and categorized the general strategies to adjust of the structure and composition for CO2 RR, such as tip effect, defect engineering, crystal plane catalysis, synergistic effect, nanoconfinement effect and so on. Eventually, we provided a prospect of the future challenges for further development and progress in CO2 RR. Previous reviews have summarized catalyst designs for the reduction of CO2 to multi-carbon products, while lacking in targeting C2 H4 alone, an important industrial feedstock. This Review mainly aims to provide a comprehensive understanding for the design strategies and challenges of electrocatalytic CO2 reduction to C2 H4 through recent researches and further propose some guidelines for the future design of copper-based catalysts for electroreduction of CO2 to C2 H4 .

Tin Nanoclusters Confined in Nitrogenated Carbon for the Oxygen Reduction Reaction.

The oxygen reduction reaction is essential for fuel cells and metal-air batteries in renewable energy technologies. Developing platinum-group-metal (PGM)-free catalysts with comparable catalytic performance is highly desired for cost efficiency. Here, we report a tin (Sn) nanocluster confined catalyst for the electrochemical oxygen reduction. The catalyst was fabricated by confining 1-1.5 nm sized Sn nanoclusters in situ in microporous nitrogen-doped carbon polyhedra (SnxNC) with an average pore size of 0.7 nm. SnxNC exhibited high catalytic performance in acidic media, including positive onset and half-wave potentials, comparable to those of the state-of-the-art Pt/C and far exceeding those of the Sn single-atom catalyst. Combined structural and theoretical analyses reveal that the confined Sn nanoclusters, which have favorable oxygen adsorption behaviors, are responsible for the high catalytic performance, but not Sn single atoms.

A Controllable Dual Interface Engineering Concept for Rational Design of Efficient Bifunctional Electrocatalyst for Zinc-Air Batteries.

Searching for bifunctional noble-free electrocatalysts with high activity and stability are urgently demanded for the commercial application of zinc-air batteries (ZABs). Herein, the authors propose a controllable dual interface engineering concept to design a noble-metal-free bifunctional catalyst with two well-designed interfaces (Ni3 FeN|MnO and MnO|CNTs) via a simple etching and wet chemical route. The heterointerface between MnO and Ni3 FeN facilitates the charge transfer rate during surface reaction, and heterointerface between MnO and carbon nanotubes (CNTs) support provides effective electron transfer path, while the CNTs matrix builds free diffusion channels for gas and electrolyte. Benefiting from the advantages of dual interfaces, Ni3 FeN/MnO-CNTs show superior oxygen reduction reaction and oxygen evolution reaction catalytic activity with an ultralow polarization gap (∆E) of 0.73 V, as well as preferable durability and rapid reaction kinetics. As proof of concept, the practical ZAB with Ni3 FeN/MnO-CNT exhibits high power density of 197 mW cm-2 and rate performance up to 40 mA cm-2 , as well as superior cycling stability over 600 cycles, outperforming the benchmark mixture of Pt/C and RuO2 . This work proposes a controllable dual interface engineering concept toward regulating the charge, electron, and gas transfer to achieve efficient bifunctional catalysts for ZABs.

Carbon-Based Electrocatalysts for Efficient Hydrogen Peroxide Production.

Hydrogen peroxide (H2 O2 ) is an environment-friendly and efficient oxidant with a wide range of applications in different industries. Recently, the production of hydrogen peroxide through direct electrosynthesis has attracted widespread research attention, and has emerged as the most promising method to replace the traditional energy-intensive multi-step anthraquinone process. In ongoing efforts to achieve highly efficient large-scale electrosynthesis of H2 O2 , carbon-based materials have been developed as 2e- oxygen reduction reaction catalysts, with the benefits of low cost, abundant availability, and optimal performance. This review comprehensively introduces the strategies for optimizing carbon-based materials toward H2 O2 production, and the latest advances in carbon-based hybrid catalysts. The active sites of the carbon-based materials and the influence of coordination heteroatom doping on the selectivity of H2 O2 are extensively analyzed. In particular, the appropriate design of functional groups and understanding the effect of the electrolyte pH are expected to further improve the selective efficiency of producing H2 O2 via the oxygen reduction reaction. Methods for improving catalytic activity by interface engineering and reaction kinetics are summarized. Finally, the challenges carbon-based catalysts face before they can be employed for commercial-scale H2 O2 production are identified, and prospects for designing novel electrochemical reactors are proposed.

Unusual Role of Point Defects in Perovskite Nickelate Electrocatalysts.

Low-cost transition-metal oxide is regarded as a promising electrocatalyst family for an oxygen evolution reaction (OER). The classic design principle for an oxide electrocatalyst believes that point defect engineering, such as oxygen vacancies (VO..) or heteroatom doping, offers the opportunities to manipulate the electronic structure of material toward optimal OER activity. Oppositely, in this work, we discover a counterintuitive phenomenon that both VO.. and an aliovalent dopant (i.e., proton (H+)) in perovskite nickelate (i.e., NdNiO3 (NNO)) have a considerably detrimental effect on intrinsic OER performance. Detailed characterizations unveil that the introduction of these point defects leads to a decrease in the oxidative state of Ni and weakens Ni-O orbital hybridization, which triggers the local electron-electron correlation and a more insulating state. Evidenced by first-principles calculation using the density functional theory (DFT) method, the OER on nickelate electrocatalysts follows the lattice oxygen mechanism (LOM). The incorporation of point defect increases the energy barrier of transformation from OO*(VO) to OH*(VO) intermediates, which is regarded as the rate-determining step (RDS). This work offers a new and significant perspective of the role that lattice defects play in the OER process.

Revealing Isolated M-N3 C1 Active Sites for Efficient Collaborative Oxygen Reduction Catalysis.

Single atom catalysts (SACs) are of great importance for oxygen reduction, a critical process in renewable energy technologies. The catalytic performance of SACs largely depends on the structure of their active sites, but explorations of highly active structures for SAC active sites are still limited. Herein, we demonstrate a combined experimental and theoretical study of oxygen reduction catalysis on SACs, which incorporate M-N3 C1 site structure, composed of atomically dispersed transition metals (e.g., Fe, Co, and Cu) in nitrogenated carbon nanosheets. The resulting SACs with M-N3 C1 sites exhibited prominent oxygen reduction catalytic activities in both acidic and alkaline media, following the trend Fe-N3 C1 > Co-N3 C1 > Cu-N3 C1 . Theoretical calculations suggest the C atoms in these structures behave as collaborative adsorption sites to M atoms, thanks to interactions between the d/p orbitals of the M/C atoms in the M-N3 C1 sites, enabling dual site oxygen reduction.

Solar-Driven Nitrogen Fixation Catalyzed by Stable Radical-Containing MOFs: Improved Efficiency Induced by a Structural Transformation.

Herein we present a new viologen-based radical-containing metal-organic framework (RMOF) Gd-IHEP-7, which upon heating in air undergoes a single-crystal-to-single-crystal transformation to generate Gd-IHEP-8. Both RMOFs exhibit excellent air and water stability as a result of favorable radical-radical interactions, and their long-lifetime radicals result in wide spectral absorption in the range 200-2500 nm. Gd-IHEP-7 and Gd-IHEP-8 show excellent activity toward solar-driven nitrogen fixation, with ammonia production rates of 128 and 220 µmol h-1 g-1 , respectively. Experiments and theoretical calculations indicate that both RMOFs have similar nitrogen fixation pathways. The enhanced catalytic efficiency of Gd-IHEP-8 versus Gd-IHEP-7 is attributed to intermediates stabilized by enhanced hydrogen bonding.

Building and identifying highly active oxygenated groups in carbon materials for oxygen reduction to H2O2.

The one-step electrochemical synthesis of H2O2 is an on-site method that reduces dependence on the energy-intensive anthraquinone process. Oxidized carbon materials have proven to be promising catalysts due to their low cost and facile synthetic procedures. However, the nature of the active sites is still controversial, and direct experimental evidence is presently lacking. Here, we activate a carbon material with dangling edge sites and then decorate them with targeted functional groups. We show that quinone-enriched samples exhibit high selectivity and activity with a H2O2 yield ratio of up to 97.8 % at 0.75 V vs. RHE. Using density functional theory calculations, we identify the activity trends of different possible quinone functional groups in the edge and basal plane of the carbon nanostructure and determine the most active motif. Our findings provide guidelines for designing carbon-based catalysts, which have simultaneous high selectivity and activity for H2O2 synthesis.

Ni and Zn co-substituted Co(CO3)0.5OH self-assembled flowers array for asymmetric supercapacitors.

The supercapacitive performance of high-rate capacity and long-term cycling stability is still a big challenge for electroactive materials. Herein, Ni and Zn co-substituted Co carbonate hydroxide (NiZn-CoCH) flowers array is self-assembled on nickel foams (NFs) using l-ascorbic acid as a nanostructure inducer. The NiZn-CoCH flowers, consisting of silk-like nanosheets, are deservedly large electrode-electrolyte contact area and suitable ion-diffusion channel. The nanostructure and Ni and Zn co-substitution significantly improve energy storage performance. This electrode exhibits a high specific capacitance of 2020.8 F g-1 at 1 A g-1 with high-rate capacity (remain 80.2% at 10 A g-1) and 5000-cycle stability (almost unchanged after 1500 cycles at 10 A g-1). Additionally, an assembled asymmetric supercapacitor (ASC) device of NiZn-CoCH//activated carbon (AC) achieves a high energy density of 29.6 Wh kg-1 at a power density of 375 W kg-1 and only a 0.5% decrease of the capacitance after 2500 cycles. This facile and novel preparation method, using l-ascorbic acid, may be promising for industrial production of electroactive materials for the high-performance energy storage and conversion devices.

Structural and biochemical insights into an insect gut-specific chitinase with antifungal activity.

The antifungal activity of insect chitinase has rarely been studied. Here, we show that chitinase ChtIV, which is specifically expressed in the midgut of Asian corn borer (Ostrinia furnacalis), has antifungal activity toward phytopathogenic fungi. ChtIV exhibited high stability and mycelial hydrolytic activity in the extreme midgut environment, which has a pH of 10 and is rich in proteases. Hyper-N-glycosylation and reduced electrostatic interactions ensure the stability of ChtIV in the midgut. The structural characteristics of ChtIV are similar to two plant antifungal chitinases but distinct from an insect chitinase for cuticular chitin degradation in both the substrate-binding cleft and auxiliary binding motif. Since the phytopathogenic fungi are those that frequently invade corn, ChtIV may play a role in insect immune system and become a potential pesticide target. The crystal structures of ChtIV and its complexes with penta-N-acetylchitopentaose (a substrate) and allosamidin (an inhibitor) were obtained, which may facilitate rational design of ChtIV inhibitors as agrichemicals.

A Highly Efficient Composite Catalyst Constructed From NH2-MIL-125(Ti) and Reduced Graphene Oxide for CO2 Photoreduction.

Substantial consumption of fossil fuels causes an increase in CO2 emissions and intensifies global pollution problems, such as the greenhouse effect. Recently, a new type of ultra-low-density porous material, metal-organic frameworks (MOFs), has been developed for the photocatalytic conversion of CO2. Herein, a composite photocatalytic catalyst based on NH2-MIL-125(Ti) and reduced graphene oxide (rGO@NH2-MIL-125) was fabricated through a facile "one-pot" process. The acquired materials were characterized to obtain their structures, morphologies, and optical information. The experimental results showed that methyl formate (MF) was the predominant reaction product, and rGO@NH2-MIL-125 exhibited the highest yield of 1,116 µmol·g-1·h-1, more than twice that of pure MIL-125. The high photoactivity of rGO@NH2-MIL-125 can be ascribed to the effective spatial separation and transfer of photoinduced carriers, largely due to the synergistic effect of amino functionality and rGO incorporation. rGO@NH2-MIL-125 also displayed acceptable repeatability in cyclic runs for CO2 reduction.

Balancing hydrogen adsorption/desorption by orbital modulation for efficient hydrogen evolution catalysis.

Hydrogen adsorption/desorption behavior plays a key role in hydrogen evolution reaction (HER) catalysis. The HER reaction rate is a trade-off between hydrogen adsorption and desorption on the catalyst surface. Herein, we report the rational balancing of hydrogen adsorption/desorption by orbital modulation using introduced environmental electronegative carbon/nitrogen (C/N) atoms. Theoretical calculations reveal that the empty d orbitals of iridium (Ir) sites can be reduced by interactions between the environmental electronegative C/N and Ir atoms. This balances the hydrogen adsorption/desorption around the Ir sites, accelerating the related HER process. Remarkably, by anchoring a small amount of Ir nanoparticles (7.16 wt%) in nitrogenated carbon matrixes, the resulting catalyst exhibits significantly enhanced HER performance. This includs the smallest reported overpotential at 10 mA cm-2 (4.5 mV), the highest mass activity at 10 mV (1.12 A mgIr-1) and turnover frequency at 25 mV (4.21 H2 s-1) by far, outperforming Ir nanoparticles and commercial Pt/C.

Rational construction of triangle-like nickel-cobalt bimetallic metal-organic framework nanosheets arrays as battery-type electrodes for hybrid supercapacitors.

Reasonably designing self-supported metal-organic framework (MOF) nanoarrays is profound for applications in energy storage and conversion. Herein, we construct a triangle-like nickel-cobalt bimetallic metal-organic framework nanosheet array on nickel foam (NiCo-MOF/NF) via facile one-step hydrothermal reaction, served as battery-like electrode material for hybrid supercapacitors. By adjusting the molar ratio of Ni and Co, the optimal NiCo-MOF/NF with Ni/Co = 3:2 (3-2 NiCo-MOF/NF) produces an impressive specific capacity of 1003.5 C/g (2230 F/g) at 1 A/g, surpassing most of the previously reported MOF based electrode materials. The superior electrochemical performances may be related to their 3D well-aligned MOF nanosheets arrays, which provides enlarged electroactive areas. Meanwhile, the tight junction of electrode materials and conductive substrate nickel foam (NF) can guarantee their sufficient electric contact, contributing to fast electron transfer from electrodes to conductive substrates. Finally, a hybrid supercapacitor fabricated by the 3-2 NiCo-MOF/NF against active carbon (AC) delivers an advantageous energy density of 34.3 Wh/kg at a power density of 375 W/kg. These results certificate that such bimetallic NiCo-MOF nanosheets arrays hold great potential as novel electrode materials for hybrid supercapacitors.

Controllable fabrication of uniform ruthenium phosphide nanocrystals for the hydrogen evolution reaction.

Uniform ruthenium phosphide (Ru2P and RuP) nanocrystals grown in situ on N- and P-codoped graphene were obtained by pyrolyzing tris(triphenylphosphine) ruthenium(ii) chloride (TPP-Ru) with pyritic acid (PA). Interestingly, Ru2P and RuP can be controllably prepared by varying the molar ratio of PA to TPP-Ru. As an efficient electrocatalyst for the hydrogen evolution reaction (HER), Ru2P exhibited a better performance than RuP in alkaline medium.

Identifying the structure of Zn-N2 active sites and structural activation.

Identification of active sites is one of the main obstacles to rational design of catalysts for diverse applications. Fundamental insight into the identification of the structure of active sites and structural contributions for catalytic performance are still lacking. Recently, X-ray absorption spectroscopy (XAS) and density functional theory (DFT) provide important tools to disclose the electronic, geometric and catalytic natures of active sites. Herein, we demonstrate the structural identification of Zn-N2 active sites with both experimental/theoretical X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. Further DFT calculations reveal that the oxygen species activation on Zn-N2 active sites is significantly enhanced, which can accelerate the reduction of oxygen with high selectivity, according well with the experimental results. This work highlights the identification and investigation of Zn-N2 active sites, providing a regular principle to obtain deep insight into the nature of catalysts for various catalytic applications.

A perovskite oxide with a tunable pore-size derived from a general salt-template strategy as a highly efficient electrocatalyst for the oxygen evolution reaction.

The fabrication of a perovskite oxide with a tunable pore-size was implemented by a general inorganic salt-template strategy. As a proof-of-concept, hierarchically porous PrBa0.5Sr0.5Co1.5-Fe0.5O5+δ (PBSCF) with a surface area of 148 m2 g-1 was successfully prepared, which exhibited remarkable electrocatalytic performance for the oxygen evolution reaction.