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The polar IO-700 could effectively adsorb LiPSs and inhibit their shuttle effect, so its use as a separator modifier for Li–S batteries provides a long cycle performance with a low rate of capacity decay of 0.0487% per cycle.

By immobilization FeNx sites on the porous substrate surface, stable atomically dispersed iron electrocatalyst with high-performance and high-metal content was rationally produced in quantitative yield and large-scale via a simple two-step process.

Hydrogen technology is widely considered a novel clean energy source, and electrolysis is an effective method for hydrogen evolution. Therefore, efficient hydrogen evolution reaction (HER) catalysts are urgently needed to replace precious metal catalysts and meet ecological and environmental protection standards. Herein, Ni–Mn–P electrocatalysts are synthesized using facile electrodeposition technology. The influence of the Mn addition on the catalytic behavior is studied by the comprehensive analysis of catalytic performance and morphology of the catalysts. Among them, the Ni–Mn–P0.01 catalyst exhibits small coral-like structures, greatly improving the adsorption and desorption of hydrogen ions and reducing the overpotential hydrogen evolution. Consequently, overpotential at 10 mA cm−2 electric current density is 113 mV, and the value of the Tafel slope achieves 74 mV/dec. Furthermore, the Ni–Mn–P catalyst shows long-time (20 h) stability at current densities of 10 and 60 mA/cm2. The results confirm that the synergistic effect of Ni, Mn, and P accelerates the electrochemical reaction. Meanwhile, the addition of manganese element can change the micromorphology of the catalyst, thereby exposing more active sites to participate in the reaction, enhancing water ionization, improving the catalytic performance. This study opens a new way toward improving the activity of the catalyst by adjusting Mn concentration during the electrodeposition process.

Because of their high energy density, low cost, and environmental friendliness, lithium-sulfur (Li-S) batteries are one of the potential candidates for the next-generation energy-storage devices. However, they have been troubled by sluggish reaction kinetics for the insoluble Li

Earth-abundant electrocatalysts for large-current-density water splitting under alkaline condition are desirable. Oxygen evolution reaction, which is a bottleneck of the overall water splitting, faces the problems of complicated reconstruction and deficiency in rational design of active sites. Herein, we report a series of transition metal chalcogenides for alkaline OER. Among them, FeCoNi(S) displayed a low overpotential of 293 mV to deliver a current density of 500 mA cm−2, which is in the top level of non-precious metal based OER electrocatalysts. A combination of (ex) in situ characterizations and DFT calculation shows that Ni(Fe,Co) trimetallic oxyhydroxides were the active sites for highly-efficient OER. Furthermore, for FeCoNi(S), when used as a bifunctional catalyst for water splitting, it only required a cell voltage of 1.84 V to deliver ∼500 mA cm−2 with extraordinary long-term stability over 2000 h. This work provides the comprehension of high-efficiency, robust catalysts for OER and overall water splitting at large current densities in alkaline media.

The multi-TpyCo2+-based supramolecular hydrogel presents the remolding property and shows a low overpotential of 264 mV at 10 mA cm−2 for oxygen evolution reaction (OER) and an ultrastable cycling stability over 1100 h for liquid Zn–air battery.

In-doped SnO2 nanoparticles with enhanced electron transfer from Sn species to In were synthesized. The maximum FEC1 was 96.46% at −0.75 V and JC1 reached −20.12 mA cm−2 at −0.95 V.

The rapid development of wearable devices has put forward high requirements for stable, solid-state, flexible and even stretchable energy storage systems.

The abundant defects in bismuth boosted the formate selectivity of electrocatalytic CO2 reduction.

The in situ atomization of carbon supported metal oxide nanoparticles provides a novel strategy to synthesize atomic sites supported on highly graphitized carbon materials with high metal loading and controlled atomic layers.

Designing non-noble metal electrocatalysts toward alkaline hydrogen evolution reaction (HER) with high performance at a large current density is urgent. Herein, a CoO/CoP heterostructure catalyst (termed POZ) was designed by a phosphating strategy. The strong electron transfer on the interface of CoO/CoP was experimentally and theoretically proven. POZ showed a low overpotential of 236 mV at 400 mA/cm2, which was 249 mV lower than non-phosphated sample. It also exhibited a remarkable solar-to-hydrogen conversion efficiency of 10.5%. In this work, the construction of CoO/CoP interface realized by a simple phosphating strategy could provide an important reference to boost the HER performance on those materials not merely metal oxides.

To utilize intermittent renewable energy as well as achieve the goals of peak carbon dioxide emissions and carbon neutrality, various electrocatalytic devices have been developed. However, the electrocatalytic reactions, e.g., hydrogen evolution reaction/oxygen evolution reaction in overall water splitting, polysulfide conversion in lithium-sulfur batteries, formation/decomposition of lithium peroxide in lithium-oxygen batteries, and nitrate reduction reaction to degrade sewage, suffer from sluggish kinetics caused by multielectron transfer processes. Owing to the merits of accelerated charge transport, optimized adsorption/desorption of intermediates, raised conductivity, regulation of the reaction microenvironment, as well as ease to combine with geometric characteristics, the built-in electric field (BIEF) is expected to overcome the above problems. Here, we give a Review about the very recent progress of BIEF for efficient energy electrocatalysis. First, the construction strategies and the characterization methods (qualitative and quantitative analysis) of BIEF are summarized. Then, the up-to-date overviews of BIEF engineering in electrocatalysis, with attention on the electron structure optimization and reaction microenvironment modulation, are analyzed and discussed in detail. In the end, the challenges and perspectives of BIEF engineering are proposed. This Review gives a deep understanding on the design of electrocatalysts with BIEF for next-generation energy storage and electrocatalytic devices.

Electrocatalytic CO2 reduction reaction (CO2RR) converts CO2 into valuable chemical fuels, which can effectively alleviate global warming and energy crisis. However, limited by its slow reaction rate and low product selectivity, it is urgent to design efficient, cheap, safe, and highly selective CO2RR electrocatalysts. Owing to the advantages of adjustable electronic structure, abundant active sites, low cost, environmental friendliness and excellent electrochemical performance, bimetallic chalcogenides have aroused great interest. Here, we briefly summarized different bimetallic oxides and sulfides for electrocatalytic CO2RR in the past five years. In addition, different hybridizations formed between metal atoms, including intermetallic compounds, heterostructures and metal doping, were generalized. Their positive effects on CO2RR catalytic selectivity and activity were deeply uncovered. Besides, we also put forward some views about the future research directions and perspectives in CO2RR field. This review aims to provide a reference for the rational design of bimetallic chalcogenides towards electrocatalytic CO2 reduction.

Photoreduction of CO

Interfacial degradation is the main reason for deterioration of mechanical properties of composites in hydrothermal environments. In this study, the effect of the interphase on water diffusion in two types of unidirectional continuous carbon fiber-reinforced polyamide 6 (CF/PA6) composites is investigated through experimental measurements, theoretical analysis, and numerical simulation. The moisture diffusion coefficient of composite at different environmental temperatures is characterized by water immersion tests for analyzing the barrier and accelerating effects of the interphase layer. Based on the experimental results, the three-phase Halpin–Tsai model is derived and validated, and then the critical diffusivity is obtained to quantify the interfacial effect during the diffusion process. To further validate the present three-phase Halpin–Tsai model, the stable and transient finite element models of moisture diffusion are developed. It is found that the critical diffusivity coefficient of the interphase for the CF/PA6 composite system is 7.31 times higher than that of the matrix.

It is a great challenge to develop highly active oxygen evolution reaction (OER) electrocatalysts with superior durability. In this study, a NiFe layered double hydroxide-decorated phosphide (NiFe LDH@CoP/NiP3) was constructed to display satisfactory OER activity and good stability for water splitting in alkaline media. At an overpotential of 300 mV, NiFe LDH@CoP/NiP3 achieved a current density of 82 mA cm−2 for the OER, which was 9.1 and 2.3 times that of CoP/NiP3 and NiFe LDH, respectively. Moreover, the reconstruction behavior, during which oxyhydroxides formed, was studied by a combination of X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. A synergistic effect between NiFe LDH and CoP/NiP3 was also observed for the hydrogen evolution reaction. Furthermore, when NiFe LDH@CoP/NiP3 acted as both the cathode and anode for overall water splitting, a high current density of 100 mA cm−2 was maintained for more than 275 h. In addition, under Xe light irradiation, a solar to hydrogen efficiency of 9.89% was achieved for solar-driven water splitting. This work presents the coupling of different active compositions, and can provide a reference for designing bifunctional electrocatalysts.

Owing to the energy crisis and environmental pollution, developing efficient and robust electrochemical energy storage (or conversion) systems is urgently needed but still very challenging. Next-generation electrochemical energy storage and conversion devices, mainly including fuel cells, metal-air batteries, metal-sulfur batteries, and metal-ion batteries, have been viewed as promising candidates for future large-scale energy applications. All these systems are operated through one type of chemical conversion mechanism, which is currently limited by poor reaction kinetics. Single atom catalysts (SACs) perform maximum atom efficiency and well-defined active sites. They have been employed as electrode components to enhance the redox kinetics and adjust the interactions at the reaction interface, boosting device performance. In this Review, we briefly summarize the related background knowledge, motivation and working principle toward next-generation electrochemical energy storage (or conversion) devices, including fuel cells, Zn-air batteries, Al-air batteries, Li-air batteries, Li-CO2 batteries, Li-S batteries, and Na-S batteries. While pointing out the remaining challenges in each system, we clarify the importance of SACs to solve these development bottlenecks. Then, we further explore the working principle and current progress of SACs in various device systems. Finally, future opportunities and perspectives of SACs in next-generation electrochemical energy storage and conversion devices are discussed.

Single atom catalysts (SACs) with isolated metal atoms dispersed on supports exhibit distinctive performances for electrocatalysis reactions. The designable realization of well-dispersed single metal atoms is still a great challenge owing to their ease of aggregation. Here, Mo single atomic sites (Mo-N3C) combined with some ultrasmall Mo2C/MoN clusters (Mo-SA/Mo2C-MoN-Cs, mean diameter

The development of non-precious, high-efficient and durable electrocatalysts for H2 evolution in alkaline media is highly desirable. Herein we report NiCoP nanoleaves array vertically grown on Ni foam for H2 evolution and overall water splitting via simple hydrothermal treatment and phosphorization. The self-supported NiCoP nanoleaves architecture contributes to more exposed active sites, the smaller contact resistance between catalyst and substrate, faster ion diffusion and electron transfer. As a result, the optimized electrode requires only overpotentials of 98 and 173 mV to achieve current densities of 10 and 100 mA cm−2 in 1.0 M KOH, respectively. Besides, used as both anode and cathode simultaneously, the electrode delivers current densities of 100 and 200 mA cm−2 at cell voltages of only 1.8 and 1.87 V, respectively. Moreover, the relatively high efficiency of about 11.4% for solar-driven water splitting further illustrates the application of our catalyst to sustainable development based on green technologies.

Nonprecious-metal catalysts with atomically dispersed active sites demonstrated high activity and selectivity in a series of catalysis reactions, the rational design and massive synthesis of such catalysts are of great interest but remains a huge challenge. Current approaches often require harsh conditions and tedious procedures. Here, we demonstrated a facile and scalable preparation strategy by anchoring pre-organized NiNx site on the surface of a layered Co-methylimidazole coordination compound. In two simple steps, single-site Ni electro-catalyst can be synthesized up to kilogram-scale with a yield of 75% under mild conditions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. Besides, it has tunable catalysis activity, high catalysis reproducibility and stability. The atomically dispersed NiNx sites are tolerate with high Ni concentration, indicating that the random reactions or metal nanoparticle formation generally observed at high temperature were avoided. This strategy presents a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with predictable structure.

The evolution of hydrogen from water using renewable electrical energy is a topic of current interest. Pt/C exhibits the highest catalytic activity for the H2 evolution reaction (HER), but scarce supplies and high cost limit its large-scale application. Atomic active centers in single-atom catalysts, single-atom alloys, and catalysts with two atom sorts exhibit maximum atomic efficiency, unique structure, and exceptional activity for the HER. Interactions between well-defined active sites and supports are known to affect electron transfer and dramatically accelerate the reaction. This Review first highlights methods for studying atomic active centers for the HER. Then, active sites with different coordination configurations are described. Active centers with one metal atom, two different metal atoms as well as nonmetal atoms are analyzed at the atomic scale. Finally, future research perspectives are proposed.

Small metal clusters have received increasing attention due to their attractive and superior performance in electrocatalytic energy conversion. However, the design and synthesis of well-dispersed metal clusters is a great challenge owing to their ease of aggregation. Here, we develop a biomass in situ conversion strategy to synthesize Fe single atomic sites (Fe–N4) combined with ultra-small Fe2O3 nanoclusters embedded in N, S codoped porous carbons (FeSA/FeONC/NSC) for the oxygen reduction reaction (ORR). The resultant FeSA/FeONC/NSC exhibits a high half-wave potential (E1/2 = 0.86 V vs. RHE) and an outstanding kinetic current density at 0.80 V (Jk = 32.15 mA cm−2), which even surpasses those of commercial Pt/C (E1/2 = 0.85 V, Jk = 16.5 mA cm−2). Atomic level dispersed Fe–N4 sites integrated with Fe2O3 clusters embedded in N, S-mediated carbon are mainly responsible for the excellent ORR activity. More importantly, the assembled Zn–air battery can output a prominent power density of 179.0 mW cm−2 and energy density of 837.4 W h kg−1 along with robust stability, outperforming the commercial Pt/C and most non-platinum catalysts. This work opens up an avenue for biomass in situ conversion into non-precious metal electrocatalysts for energy conversion and storage technologies.

Chemical vapor deposition (CVD) is recognized as a powerful tool to synthesize atomically thin two-dimensional (2D) nanomaterials with the merits of high quality and uniform thickness with high efficiency, controllability, and scalability. Benefitting from the intriguing electronic and chemical characteristics, 2D transition metal dichalcogenides (TMDs) have attracted increasing attention with regard to energy-related electrocatalysis, including H2 evolution, CO2 reduction, O2 reduction/evolution, I3− reduction, etc. Atomic-scale tailoring of the surface and interface of CVD-grown TMDs is critical to not only improve the electronic structure and conductivity but also understand the intrinsic nature of the active sites. Therefore, a comprehensive and deeper understanding of CVD-grown 2D TMDs for use in electrocatalysis is urgently needed. In this review, the very recent advances in surface and interface engineering strategies, such as geometric dimensional control, defect engineering, doping modification, phase transition, strain tuning, and heterostructure construction, have been highlighted. Finally, the current challenges and perspectives are discussed. This review aims to provide the profound understanding and design of atomic-scale active sites in 2D TMDs for use in energy electrocatalysis.

The electrochemical CO2 reduction reaction (CO2RR) to eliminate excess CO2 and produce fuels/chemicals under mild conditions provides a sustainable way to maintain carbon balance and alleviate the energy shortage. However, the low current density, competitive H2 evolution reaction and uncontrollable product distribution are urgent to be solved. Benefiting from the well-defined active centers in single atom catalysts (SACs), the coordination bond, bond length/angle, etc. can be modulated to affect the selectivity/activity towards the CO2RR, which relies on electron transfer, adsorption states and so on. Hence, an in-depth summary about the regulation of the coordination structure for the CO2RR is significant and pressing. This review concentrates on the manipulation of central atoms and coordination atoms on carbon and other supports in SACs for the CO2RR. As a prototype, a definitive correlation between the structure and XAFS spectra characteristics was properly decoded. Then, the influence of the coordination atoms and coordination number on the current density, reduction products, reaction path, etc., is highlighted. Finally, prospects such as identification of the coordination structure, machine learning, fine adjustment of the coordination atoms and control of the product distribution were put forward. This Review contributes profound insights for the rational design of the coordination structure towards highly efficient and even guided electrocatalytic CO2 reduction.

We demonstrate a charge transfer boosted hydrogen (H2) evolution of transition metal oxides via a Schottky junction. The FeNi and metallic defect-rich CoFe2O4 (DCF) as well as semiconducting nitrogen-doped carbon (NC), named as FeNi/DCF/NC, possessed only 6.5% charge transfer resistance of DCF. Theoretical calculations indicate that the enhanced electron movement happened from FeNi/DCF to NC. The H2 evolution activity of FeNi/DCF/NC showed 5.8-fold improvement compared to that of DCF at the overpotential of 400 mV in 1.0 M KOH. This work provides an effective way to enhance the electrocatalytic activity of oxides for the H2 evolution reaction and related reactions.

Herein, a novel dual single-atom catalyst comprising adjacent Fe-N

Photoreduction of CO2 into solar fuels has received great interest, but suffers from low catalytic efficiency and poor selectivity. Herein, two single-Cu-atom catalysts with unique Cu configurations in phosphorus-doped carbon nitride (PCN), namely, Cu1N3@PCN and Cu1P3@PCN were fabricated via selective phosphidation, and tested in visible light-driven CO2 reduction by H2O without sacrificial agents. Cu1N3@PCN was exclusively active for CO production with a rate of 49.8 μmolCO gcat−1 h−1, outperforming most polymeric carbon nitride (C3N4) based catalysts, while Cu1P3@PCN preferably yielded H2. Experimental and theoretical analysis suggested that doping P in C3N4 by replacing a corner C atom upshifted the d-band center of Cu in Cu1N3@PCN close to the Fermi level, which boosted the adsorption and activation of CO2 on Cu1N3, making Cu1N3@PCN efficiently convert CO2 to CO. In contrast, Cu1P3@PCN with a much lower Cu 3d electron energy exhibited negligible CO2 adsorption, thereby preferring H2 formation via photocatalytic H2O splitting.

It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron-hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO2 support (Pt1 /def-TiO2 ). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO2 units to generate surface oxygen vacancies and form a Pt-O-Ti3+ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt-O-Ti3+ atomic interface effectively facilitates photogenerated electrons to transfer from Ti3+ defective sites to single Pt atoms, thereby enhancing the separation of electron-hole pairs. This unique structure makes Pt1 /def-TiO2 exhibit a record-level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h-1 , exceeding the Pt nanoparticle supported TiO2 catalyst by a factor of 591.

Quasi-solid-state Zn-air batteries (ZABs) have shown extraordinary promise for electrochemical energy storage, but are usually limited to relatively low-rate ability (< 10 mA cm−2), which caused by the sluggish O2 electrocatalysis and unstable electrochemical interface. Here we present an ultrahigh-rate and robust quasi-solid-state ZABs integrated with the atomic Co-N4 sites anchored on wrinkled nitrogen-doped graphene (Co SA-NDGs) cathode and the modulated H-bond network of polyacrylamide (PAM) organohydrogel electrolyte with. The quasi-solid-state ZABs exhibit the highest cycling rate of 100 mA cm−2 over 50 h at room temperature, which is nearly an order of magnitude higher than results reported previously. Meanwhile, the exceptional cycling stability more than 300 h (0.5 mA cm−2) with high-capacity retention at -60 oC and all-temperature adaptability (-60 to 60°C) are also demonstrated. The integral design towards high performance Zn-air batteries using atomic site catalyst and electrolyte with good interface stability broaden the scope of application.