Treasure-bowl style bifunctional site in cerium-tungsten hetero-clusters for superior solar-driven hydrogen production.

Electrochemical water splitting powered by renewable energy sources hold potential for clean hydrogen production. However, there is still persistent challenges such as low solar-to-hydrogen conversion efficiency and sluggish oxygen evolution reactions. Here, we address the poor kinetics by studying and strengthening the coupling between Ce and W, and concurrently establishing Ce-W bi-atomic clusters on P,N-doped carbon (WN/WC-CeO2-x@PNC) with a "treasure-bowl" style. The bifunctional active sites are established using a novel and effective self-sacrificial strategy involving in situ induced defect formation. In addition, by altering the coupling of the W(d)-N(p) and W(d)-Ce(f) orbitals in the WN/WC-CeO2-x supramolecular clusters, we are able to disrupt the linear relationship between the binding energies of reaction intermediates, a key to obtain high catalytic performance for transition metals. Through the confinement of the WN/WC-CeO2-x composite hetero-clusters within the sub-nanometre spaces of hollow nano-bowl-shaped carbon reactors, a stable and efficient hydrogen production via water electrolysis could be achieved. When assembled together with a solar GaAs triple junction solar cell, a solar-to-hydrogen conversion efficiency of 18.92% in alkaline media could be realized. We show that the key to establish noble metal free catalysts with high efficiency lies in the fine-tuning of the metal-metal interface, forming regions with near optimal adsorption energies for the reaction intermediates participating in water electrolysis.

Recent Advances in Catalyst Design and Performance Optimization of Nanostructured Cathode Materials in Zinc-Air Batteries.

This review focuses on the advanced design and optimization of nanostructured zinc-air batteries (ZABs), with the aim of boosting their energy storage and conversion capabilities. The findings show that ZABs favor porous nanostructures owing to their large surface area, and this enhances the battery capacity, catalytic activity, and life cycle. In addition, the nanomaterials improve the electrical conductivity, ion transport, and overall battery stability, which crucially reduces dendrite growth on the zinc anodes and improves cycle life and energy efficiency. To obtain a superior performance, the importance of controlling the operational conditions and using custom nanostructural designs, optimal electrode materials, and carefully adjusted electrolytes is highlighted. In conclusion, porous nanostructures and nanoscale materials significantly boost the energy density, longevity, and efficiency of Zn-air batteries. It is suggested that future research should focus on the fundamental design principles of these materials to further enhance the battery performance and drive sustainable energy solutions.

Pomelo peel biomass derived highly active advanced-oxidation-process catalyst: Complete elimination of organic pollutants.

The advanced oxidation process (AOPs) is playing an important role in the elimination of hazardous organic pollutants, but the development of inexpensive and highly active advanced catalysts is facing challenges. In this study, a low-cost and readily available agricultural waste resource pomelo peel-flesh (PPF) biomass was used as the basic raw material, and the uniformly dispersed small cobalt nanoparticles were effectively anchored in the biochar derived from pomelo peel-flesh (BDPPF) by impregnation adsorption/complexation combined with heat treatment. Co/BDPPF (BDPPF embedded with Co) can effectively activate peroxymonosulfate (PMS) to SO4·-, ·OH and 1O2 reactive oxygen species, and achieve nearly 100% degradation of tetracycline persistent organic pollutant. Co/BDPPF can not only degrade tetracycline efficiently in complex water environment, but also degrade most organic pollutants universally, and has long-term stability, which solves the problem of poor universality and stability of heterogeneous catalysts to a certain extent. Importantly, Co/BDPPF derived from waste biomass was also innovatively designed as the core of an integrated continuous purification device to achieve continuous purification of organic wastewater. In this study, agricultural waste resources were selected as biomass raw materials to achieve efficient capture of Co2+, and finally developed advanced AOPs catalyst with excellent performance to achieve the purification of organic wastewater. It also provides a promising solution for the preparation of simple, low-cost, large-scale production of AOPs catalysts that can be put into actual production.

Recent advances in alginate-based composite gel spheres for removal of heavy metals.

The discharge of heavy metal ions from industrial wastewater into natural water bodies is a consequence of global industrialisation. Due to their high toxicity and resistance to degradation, these heavy metal ions pose a substantial threat to human health as they accumulate and amplify. Alginate-based composite gels exhibit good adsorption and mechanical properties, excellent biodegradability, and non-toxicity, making them environmentally friendly heavy metal ion adsorbents for water with promising development prospects. This paper introduces the basic properties, cross-linking methods, synthetic approaches, modification methods, and manufacturing techniques of alginate-based composite gels. The adsorption properties and mechanical strength of these gels can be enhanced through surface modification, multi-component mixing, and embedding. The main production processes involved are sol-gel and cross-linking methods. Additionally, this paper reviews various applications of alginate composite gels for common heavy metals, rare earth elements, and radionuclides and elucidates the adsorption mechanism of alginate composite gels. This study aimed to provide a reference for synthesising new, efficient, and environmentally friendly alginate-based adsorbents and to contribute new ideas and directions for addressing the issue of heavy metal pollution.

Salted Dried Bamboo Shoots-Derived Mesoporous Carbon Inherently Doped with SiC and Nitrogen for Capacitive Deionization.

Dried bamboo shoots (DBS) are a natural resource with inherent silica content, which can serve as sacrificial templates for the formation of mesoporous carbon but also promote the generation of silicon carbide (SiC). Building on this, we introduced mesoporous and graphitic carbon/SiC (SiC/BSC) as the CDI electrode for copper ion (Cu2+) removal. Mesoporous carbon electrodes facilitate faster ion transport, diffusion, and electron-transfer pathways. Furthermore, SiC accelerates electron transfer and promotes faradic redox reactions during the charge and discharge processes. Consequently, the synergistic effect of SiC/BSC mesoporous carbon material leads to a promising electrode for Cu2+ capacitive deionization. Leveraging these unique properties, the SiC/BSC electrode material exhibits an outstanding CDI performance of 381.5 mg/g at 1.8 V. This study offers a strategy for the preparation of efficient mesoporous carbon materials as CDI electrodes, specifically tailored for the deionization of Cu2+ ions.

C3N5-based nanomaterials and their applications in heterogeneous catalysts, energy harvesting, and environmental remediation.

Over the past few decades, the global reliance on fossil fuels and the exponential growth of human population have escalated global energy consumption and environmental issues. To tackle these dual challenges, metal catalysts, in particular precious metal ones, have emerged as pivotal players in the fields of environment and energy. Among the numerous metal-free and organic catalyst materials, C3N5-based materials have a major advantage over their carbon nitride (CxNy) counterparts owing to the abundant availability of raw materials, non-toxicity, non-hazardous nature, and exceptional performance. Although significant efforts have been dedicated to synthesising and optimising the applicable properties of C3N5-based materials in recent years, a comprehensive summary of the immediate parameters of this promising material is still lacking. Given the rapid development of C3N5-based materials, a timely review is essential for staying updated on their strengths and weaknesses across various applications, as well as providing guidance for designing efficient catalysts. In this study, we present an extensive overview of recent advancements in C3N5-based materials, encompassing their physicochemical properties, major synthetic methods, and applications in photocatalysis, electrocatalysis, and adsorption, among others. This systematic review effectively summarises both the advantages and shortcomings associated with C3N5-based materials for energy and environmental applications, thus offering researchers focussed on CxNy-materials an in-depth understanding of those based on C3N5. Finally, considering the limitations and deficiencies of C3N5-based materials, we have proposed enhancement schemes and strategies, while presenting personal perspectives on the challenges and future directions for C3N5. Our ultimate aim is to provide valuable insights for the research community in this field.

ZIF-67 based CoS2 self-assembled on graphitic carbon nitride microtubular for sensitive electrochemical detection of paraquat in fruits.

Paraquat (PQ) is a widely used and harmful herbicide that must be detected in the environment. This study reports a novel composite (CoS2-GCN) prepared by assembling cobalt disulfide (CoS2) derived from metal-organic frameworks (MOFs) on graphitic carbon nitride (GCN). An electrochemical sensor (CoS2-GCN/ glassy carbon electrode (GCE)) was successfully prepared by modifying CoS2-GCN onto a GCE to sensitively detect PQ. Different concentrations of PQ were detected using square-wave voltammetry, and the CoS2-GCN/GCE electrochemical sensor showed remarkable response signals for PQ in the range of 20 - 1000 nM and 1 - 13 µM, with a detection limit of 4.13 nM (S/N = 3). The CoS2-GCN/GCE electrochemical sensor exhibited high stability, reproducibility, and immunity to interference, which were attributed to the synergistic effects of CoS2 and GCN. In addition, the CoS2-GCN/GCE electrochemical sensor showed high applicability for the analysis of fruit samples. Therefore, the proposed sensor has potential applications in PQ detection.

Nitrogen-bridged Fe-Cu Atomic Pair Sites for Efficient Electrochemical Ammonia Production and Electricity Generation with Zn-NO2 Batteries.

The development of environmentally sustainable and highly efficient technologies for ammonia production is crucial for the future advancement of carbon-neutral energy systems. The nitrite reduction reaction (NO2 RR) for generating NH3 is a promising alternative to the low-efficiency nitrogen reduction reaction (NRR), owing to the low N=O bond energy and high solubility of nitrite. In this study, we designed a highly efficient dual-atom catalyst with Fe-Cu atomic pair sites (termed FeCu DAC), and the as-developed FeCu DAC was able to afford a remarkable NH3 yield of 24,526 µg h-1 mgcat. -1 at -0.6 V, with a Faradaic Efficiency (FE) for NH3 production of 99.88 %. The FeCu DAC also exhibited exceptional catalytic activity and selectivity in a Zn-NO2 battery, achieving a record-breaking power density of 23.6 mW cm-2 and maximum NH3 FE of 92.23 % at 20 mA cm-2 . Theoretical simulation demonstrated that the incorporation of the Cu atom changed the energy of the Fe 3d orbital and lowered the energy barrier, thereby accelerating the NO2 RR. This study not only demonstrates the potential of galvanic nitrite-based cells for expanding the field of Zn-based batteries, but also provides fundamental interpretation for the synergistic effect in highly dispersed dual-atom catalysts.

Nonstoichiometric Doping of La0.9FexSn1-xO3 Hollow Microspheres for an Ultrasensitive Formaldehyde Sensor.

Oxygen vacancies play an essential role in gas-sensitive materials, but the intrinsic oxides are poorly controlled and contain low oxygen vacancy concentrations. In this work, we prepared La0.9Fe1-xSnxO3 microspheres with high sensitivity and controllability by a simple hydrothermal method, and then, we demonstrated that it has many oxygen ion defects by X-ray photoelectron spectroscopy and electron paramagnetic resonance characterization. The gas sensor exhibited ultrahigh response, specific recognition of formaldehyde gas, and excellent moisture resistance. By comparing the composites with different doping ratios, it was found that the highest catalytic activity was reached when x = 0.75, and the response value of La0.9Fe0.75Sn0.25O3 hollow microspheres at 200 °C reached 73-10 ppm of formaldehyde, which is 188% higher than that of intrinsic LaFeO3 hollow microspheres. On the one hand, due to the absence of A-site La3+ and the replacement of B-site Fe3+ by Sn4+, a large number of oxygen vacancies are induced on the surface and in the interior of the materials; on the other hand, it is also related to the large specific surface area and gas channels caused by the particular structure.

Electrocatalytic nitrate-to-ammonia conversion on CoO/CuO nanoarrays using Zn-nitrate batteries.

Zn-NO3- batteries can generate electricity while producing NH3 in an environmentally friendly manner, making them a very promising device. However, the conversion of NO3- to NH3 involves a proton-assisted 8-electron (8e-) transfer process with a high kinetic barrier, requiring high-performance catalysts to realize the potential applications of this technology. Herein, we propose a heterostructured CoO/CuO nanoarray electrocatalyst prepared on a copper foam (CoO/CuO-NA/CF) that can electrocatalytically and efficiently convert NO3- to NH3 at low potential and achieves a maximum NH3 yield of 296.9 µmol h-1 cm-2 and the Faraday efficiency (FE) of 92.9% at the -0.2 V vs. reversible hydrogen electrode (RHE). Impressively, Zn-NO3- battery based on the monolithic CoO/CuO-NA/CF electrode delivers a high NH3 yield of 60.3 µmol h-1 cm-2, FENH3 of 82.0%, and a power density of 4.3 mW cm-2. This study provides a paradigm for heterostructured catalyst preparation for the energy-efficient production of NH3 and simultaneously generating electrical energy.

MOF-on-MOF-Derived Ultrafine Fe2P-Co2P Heterostructures for High-Efficiency and Durable Anion Exchange Membrane Water Electrolyzers.

The alkaline hydrogen evolution reaction (HER) in an anion exchange membrane water electrolyzer (AEMWE) is considered to be a promising approach for large-scale industrial hydrogen production. Nevertheless, it is severely hampered by the inability to operate tolerable HER catalysts consistently under low overpotentials at ampere-level current densities. Here, we develop a universal ligand-exchange (MOF-on-MOF) modulation strategy to synthesize ultrafine Fe2P and Co2P nanoparticles, which are well anchored on N and P dual-doped carbon porous nanosheets (Fe2P-Co2P/NPC). In addition, benefiting from the downshift of the d-band center and the interfacial Co-P-Fe bridging, the electron-rich P site is triggered, which induces the redistribution of electron density and the swapping of active centers, lowering the energy barrier of the HER. As a result, the Fe2P-Co2P/NPC catalyst only requires a low overpotential of 175 mV to achieve a current density of 1000 mA cm-2. The solar-driven water electrolysis system presents a record-setting and stable solar-to-hydrogen conversion efficiency of 20.36%. Crucially, the catalyst could stably operate at 1000 mA cm-2 over 1000 h in a practical AEMWE at an estimated cost of US$0.79 per kilogram of H2, which achieves the target (US$2 per kg of H2) set by the U.S. Department of Energy (DOE).

A macroporous carbon nanoframe for hosting Mott-Schottky Fe-Co/Mo2C sites as an outstanding bi-functional oxygen electrocatalyst.

Simultaneously optimizing the d-band center of the catalyst and the mass/charge transport processes during the oxygen catalytic reaction is an essential but arduous task in the pursuit of creating effective and long-lasting bifunctional oxygen catalysts. In this study, a Fe-Co/Mo2C@N-doped carbon macroporous nanoframe was successfully synthesized via a facile "conformal coating and coordination capture" pyrolysis strategy. As expected, the resulting heterogeneous electrocatalyst exhibited excellent reversible oxygen electrocatalytic performance in an alkaline medium, as demonstrated by the small potential gap of 0.635 V between the operating potential of 1.507 V at 10 mA cm-2 for the oxygen evolution reaction and the half-wave potential of 0.872 V towards the oxygen reduction reaction. Additionally, the developed Zn-air battery employing the macroporous nanoframe heterostructure displayed an impressive peak power density of 218 mW cm-2, a noteworthy specific capacity of 694 mA h gZn-1, and remarkable charging/discharging cycle durability. Theoretical calculations confirmed that the built-in electric field between the Fe-Co alloy and Mo2C semiconductor could induce advantageous charge transport and redistribution at the heterointerface, contributing to the optimization of the d-band center of the nanohybrid and ultimately leading to a reduction in the reaction energy barrier during catalytic processes. The exquisite macroporous nanoframe facilitated the rapid transport of ions and charges, as well as the smooth access of oxygen to the internal active site. Thus, the presented unique electronic structure regulation and macroporous structure design show promising potential for the development of robust bifunctional oxygen electrodes.

Mn, N co-doped carbon nanospheres for efficient capture of uranium (VI) via capacitive deionization.

Heteroatom doping, involving the introduction of atoms with distinct electronegativity into carbon materials, has emerged as an effective approach to optimize their charge distribution. In this study, we designed a strategy to synthesize in-situ Mn, N co-doped carbon nanospheres (Mn-NC) through the polycondensation of 2,6-diaminopyridine and formaldehyde in synchronization with Mn2+ chelation to form Mn-polytriazine precursor, followed by calcination to form carbonaceous solid. Then Mn-NC was fabricated into a capacitive deionization (CDI) electrode for the selective removal of uranium ions (U (VI)), which is commonly found in radioactive water. Interestingly, Mn-NC exhibited good selectivity for UO22+ capture with a demonstrated adsorption capacity of approximately 194 mg/g @1.8 V. The systematic analysis of the adsorption mechanism of UO22+ revealed that N dopants within Mn-NC can coordinate with the U (VI) ions, thereby facilitating the removal process. Our study presents a straightforward and convenient strategy for removing UO22+ ions by harnessing the coordination effect, eliminating the requirement for pore size control.

Separable alginate gel spheres encapsulated with La-Fe modified biochar for efficient adsorption of Sb(III) with high capacity.

Sb and its compounds have been widely used in various industrial applications. Therefore, the preparation of Sb adsorbents with easy recovery and excellent adsorption levels is an urgent problem that must be resolved. By calcining and treating La/Fe metal-organic frameworks (MOF) biochar as a precursor, a loaded La-Fe-modified water hyacinth biochar was synthesised and used as a filler to synthesise iron alginate composite gel spheres, MBC/algFe. Through a series of static adsorption experiments, the effects of different filler addition ratios, solution pH, reaction time, coexisting ions, and other factors on the adsorption of Sb(III) were investigated. According to the Langmuir model, the maximum adsorption capacity of MBC/algFe at 25 â„ƒ was 277.8 mg·g-1. The adsorption mechanism mainly involved hydrogen bonding and metal-organic complexation interactions.

Double-Confinement Construction of Atomically-Dispersed-Fe Bifunctional Oxygen Electrocatalyst for High-Performance Zinc-Air Battery.

Simultaneously achieving high activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the key to constructing rechargeable Zn-air batteries (ZABs). Here the complexation of 1,10-phenanthroline and the spatial confinement effect of closo-[B12 H12 ]2- are used to solidify metal-boron-cluster-organic-polymers on the surface of SiO2 microspheres to construct a bifunctional oxygen electrocatalyst (FeBCN/NHCS). Driven by FeBCN/NHCS, the half-wave-potential of ORR surpasses that of the Pt/C catalyst, reaching 0.893 V versus RHE, and the overpotential (η10 ) of OER is as low as 361 mV. The ZABs of FeBCN/NHCS as an air cathode not only have high power density and specific capacity, but also have charge-discharge durability. The FeBCN/NHCS is not only related to the high specific surface area, but also the high exposure rate of single-atom Fe and the doping of heteroatom B. This study provides an efficient oxygen electrocatalyst and also contributes wisdom to the acquisition of highly active oxygen electrocatalyst.

Separable calcium sulphate modified biochar gel beads for efficient cadmium removal from wastewater.

This study outlines the synthesis of a novel, cost-effective composite material comprising calcium sulphate-modified biochar (Ca-BC) cross-linked with polyethyleneimine (PEI) and sodium alginate (SA), which was subsequently transformed into gel beads (Ca-BC@PEI-SA). These beads were engineered to enable effective cadmium ion (Cd(II)) adsorption from wastewater. Batch adsorption experiments were conducted to evaluate the effects of pH, contact time, temperature, and coexisting ions on adsorption performance. The isotherms and kinetics in the adsorption process were investigated. The results indicated that the removal of Cd(II) by Ca-BC@PEI-SA adheres more closely to the Langmuir model, with maximum adsorption capacities of 138.44 mg/g (15 °C), 151.98 mg/g (25 °C), and 165.56 mg/g (35 °C) at different temperatures. The pseudo-secondary model fit well with Cd(II) adsorption kinetics, suggesting that the removal process was a monolayer process controlled by chemisorption. Moreover, the mechanical strength of the Ca-BC@PEI-SA gel beads allowed easy recovery and reduced secondary contamination. In addition, the adsorption capacity remained nearly constant after four cycles. The main Cd(II) adsorption mechanisms involved surface complexation, ion exchange, and cation-π-bonding interactions.

Self-supported P-doped NiFe2O4 micro-sheet arrays for the efficient conversion of nitrite to ammonia.

The nitrite reduction reaction (NO2-RR) is an important process for eliminating toxic nitrites from water while simultaneously producing high-value ammonia under ambient conditions. For the aim to improve the NO2-RR efficiency, we designed a new synthetic strategy to prepare a phosphorus-doped three-dimensional NiFe2O4 catalyst loaded onto a nickel foam in-situ and evaluated its performance for the reduction of NO2- to NH3. The catalyst achieved a high Faradaic efficiency (FE) of 95.39%, and an ammonia (NH3) yield rate of 34788.51 µg h-1 cm-2 at - 0.45 V vs. RHE. A high NH3 yield rate and FE were maintained after 16 cycles at - 0.35 V vs. RHE in an alkaline electrolyte. This study provides a new direction for the rational design of highly stable electrocatalysts for the conversion of NO2- to NH3.

MoS2 nanosheets grown on bowl-shaped hollow carbon spheres as an efficient electrochemical sensor for ultrasensitive determination of nephrotoxic aristolochic acids in Chinese traditional herbs.

Aristolochic acid, a substance in herbs, is highly nephrotoxic, so it is crucial to develop an assay that can rapidly and accurately analyze its content. In this study, bowl-shaped hollow carbon spheres (BHCs) were synthesized using a complex template method, and a MoS2 layer was grown in situ on their surface using a hydrothermal method. The synthesized MoS2-BHCs were used to fabricate an electrochemical sensor for the ultrasensitive and highly selective detection of aristolochic acids (AAs). The optimal conditions for AA detection were determined by tailoring the amount of MoS2 used to modify the BHCs and the pH of the electrolyte. Under optimal conditions, the MoS2-BHC-based sensor presented excellent AA detection performance. The linear concentration ranges of the MoS2-BHC-based sensor for the detection of AA were 0.05-10 µmol L-1 and 10-80 µmol L-1, and the limit of detection of the sensor was 14.3 nmol L-1. Moreover, the MoS2-BHC-based sensor detected AA in Aristolochia and Asarum sieboldii samples. The results were consistent with high-performance liquid chromatography data, demonstrating the satisfactory recovery and accuracy of the sensor. Therefore, we believe that MoS2-BHC-based sensors can be used as effective platforms for detecting AA in traditional Chinese herbs.

Interface engineering induced charge rearrangement boosting reversible oxygen electrocatalysis activity of heterogeneous FeCo-MnO@N-doped carbon nanobox.

The advancement of bifunctional oxygen catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is imperative yet challenging for the optimization of Zn-air batteries. In this study, we reported the successful incorporation of a novel Mott-Schottky catalytic site within a MnO-FeCo heterojunction into an N-doping carbon nanobox, taking into consideration the effects of the intrinsic electric field and hollow/porous support carriers for electrocatalyst design. As expected, the resulting heterogeneous catalyst exhibited an encouraging half-wave potential of 0.88 V and an impressive limiting-current density of 5.62 mA/cm2 for the ORR, as well as a minimal overpotential of 271 mV at 10 mA/cm2 for the OER, both in alkaline conditions. Furthermore, the Zn-air battery constructed with the heterojunction nanobox product displayed a decent potential gap of 0.621 V, an outstanding power density of 253 mW/cm2, a considerable specific capacity of 761 mAh/gZn, and exceptional stability, with up to 336 h of cycling charging and discharging operation. Consequently, this method of modulating the catalyst's surface charge distribution through an internal electric field at the interface and facilitating mass transport offers a novel avenue for the development of robust bifunctional oxygen catalysts.

Boron-cluster-based porous BCN material modified electrode for electrochemical determination of morphine in serum.

Porous highly boron-doped BCN (p-BCN) was produced by using a boron cluster salt (closo-[B12H12]2-) as the boron-based precursor and SiO2 as a hard template. The synthesized p-BCN was used in an electrochemical sensor for the ultrasensitive and highly selective detection of morphine (MOP). The optimal conditions for MOP detection were determined by optimizing the experimental conditions. Under these optimal conditions, the p-BCN-based sensor exhibited excellent MOP detection performance (working potential of 0.2 V). Specifically, it showed a detection range of 0.05 to 200 µM and a detection limit of 17.8 nM. Notably, the p-BCN-based electrochemical sensor was successfully applied to the determination of MOP in human blood, and the results showed satisfactory recovery and accuracy. Therefore, this sensor can be used as an effective platform for the detection of MOP in human blood samples.