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Mixed multiple oxidation states CoMoO4 nanowires (electrocatalysts) with tunable intrinsic oxygen vacancies were fabricated. CoMoO4 with proper oxygen vacancy can be employed to construct a Li-air battery with a high capacity and stable cyclability. This is possible because CoMoO4 contains surface oxygen vacancies, which result in the unit of CoMo bond, that is important for electrocatalysts used in Li-air batteries. Both the experimental and theoretical results demonstrate that the surface oxygen vacancies containing CoMoO4 nanowires have a higher electrocatalytic activity. This shows that the highly efficient electrocatalysts used for Li-air batteries were designed to modify the redox properties of the mixed metal oxide in the catalytic active sites. This successful material design led to an improved strategy for high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities based on the fast formation and extinction of ORR products.

Recent developments in the perovskite field have aimed at exploring cluster-based organic-inorganic copper(I) halides as novel luminescent materials because of their low toxicity and structural diversity. However, the poor framework stability and low dispersion in solvent constitute the key challenges to their practical applications such as luminescent inks. Herein, we report the preparation of highly luminescent inks via one-pot solution synthesis, which consisted of ionic Cu

Lithium oxygen (Li-O2) batteries have shown great potential as new energy-storage devices due to the high theoretical energy density. However, there are still substantial problems to be solved before practical application, including large overpotential, low energy efficiency, and poor cycle life. Herein, we have successfully synthesized a RuO2-Co3O4 nanohybrid with a rich oxygen vacancy and large specific surface area. The Li-O2 batteries based on the RuO2-Co3O4 nanohybrid shown obviously reduced overpotential and improved circulatory property, which can cycle stably for more than 100 cycles at a current density of 200 mA g-1. Experimental results and density function theory calculation prove that the introduction of RuO2 can increase oxygen vacancy concentration of Co3O4 and accelerate the charge transfer. Meanwhile, the hollow and porous structure leads to a large specific surface area about 104.5 m2 g-1, exposing more active sites. Due to the synergistic effect, the catalyst of the RuO2-Co3O4 nanohybrid can significantly reduce the adsorption energy of the LiO2 intermediate, thereby reducing the overpotential effectively.

Reasonably regulating electronic coupling to promote charge transfer and exciton separation has been regarded a promising approach in catalysis. The material engineering of van der Waals heterojunction (vdWsH) based on two-dimensional (2D) materials would be a potential way to optimize the as-prepared extrinsic physicochemical characteristics. However, it was still an almost uncultivated land waiting for exploration in catalysis. Herein, we introduced the inert h-boron nitride (h-BN) in non-metal reduced graphene oxide (GN) catalysts and constructed BN-GN vdWsH. The theoretical calculation demonstrated that the h-BN can effectively modify the electronic properties of graphene. With the introduction of h-BN, the BN-GN vdWsH can obviously enhance the catalytic activity of Li-CO2 battery. The existence of BN-GN vdWsH can reduce the overpotential more than 700 mV compared with reduced graphene oxide during the CO2 reduction reaction (CO2RR) and CO2 evolution reaction (CO2ER), and it extended cyclic stability more than three times, which was one of the most outstanding non-metallic catalysts. The reasonable structure design made it work as a high efficient electrocatalyst, which shed light on the development for functional treatment of catalytic materials.

Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal catalysts, such as cobalt oxide, with superior activity and excellent stability to other catalysts are widely desired. Nevertheless, the performance of CoO nanoparticles as an electrode material were significantly limit for its inferior conductivity, dissolution, and high cohesion. Herein, we grow ultrafine cobalt monoxide to decorate the interlayer and surface of the Ti3C2Tx nanosheets via a hydrothermal method companied by calcination. The layered MXenes act as the underlying conductive substrate, which not only increase the electron transfer rate at the interface but also greatly improve the electrochemical properties of the nanosized CoO particles by restricting the aggregation of CoO. The resulting CoO/Ti3C2Tx nanomaterial is applied as oxygen electrode for lithium-oxygen battery and achieves more than 160 cycles and first cycle capacity of 16,220 mAh g−1 at 100 mA g−1. This work paves a promising avenue for constructing a bi-functional catalyst by coupling the active component of a transition metal oxide (TMO) with the MXene materials in lithium-oxygen battery.

Urea, as a prospective energy source, is rarely utilized for lack of effective catalysts to overcome its sluggish kinetics during its electrolysis. Exploiting low-cost and high-efficiency catalysts to accelerate the urea oxidation reaction (UOR) does make sense as it can relieve not only energy shortage but also the water contamination problems. In this work, the Ni₃S₂ nanosheets grown on the Ni foam with different amounts of Mn²⁺ doping were developed as useful electrocatalysts toward UOR. The experimental and computational methods were performed to explore the properties of obtained samples. We found that the doping of Mn²⁺ could distinctly regulate the charge distribution of Ni₃S₂ by which the performance was observably optimized. We also compared the behaviors of obtained catalysts with various dopant concentrations of Mn²⁺. Especially, Ni₃S₂ grown on the Ni foam with the addition of 0.2 mmol of Mn²⁺ exhibits splendid properties with a lower potential and superior longevity, which can achieve a current density of 100 mA cm–² at a voltage of only 1.397 V (vs reversible hydrogen electrode) in 1.0 M KOH containing 0.5 M urea solution, indicating that our findings can serve as promising electrocatalysts for urea electrolysis.

NiFe layered double hydroxides (LDHs) have been denoted as benchmark non-noble-metal electrocatalysts for the oxygen evolution reaction (OER). However, for laminates of NiFe LDHs, the edge sites are active, but the basal plane is inert, leading to underutilization as catalysts for the OER. Herein, for the first time, light and electron-deficient Li ions are intercalated into the basal plane of NiFe LDHs. The results of theoretical calculations and experiments both showed that electrons would be transferred from near Ni2+ to the surroundings of Li+ , resulting in electron-deficient properties of the Ni sites, which would function as "electron-hungry" sites, to enhance surface adsorption of electron-rich oxygen-containing groups, which would enhance the effective activity for the OER. As demonstrated by the catalytic performance, the Li-NiFe LDH electrodes showed an ultralow overpotential of only 298 mV at 50 mA cm-2 , which was lower than that of 347 mV for initial NiFe LDHs and lower than that of 373 mV for RuO2 . Reasonable intercalation adjustment effectively activates laminated Ni2+ sites and constructs the electron-deficient structure to enhance its electrocatalytic activity, which sheds light on the functional treatment of catalytic materials.

Ti3C2 belongs to MXenes family, which is a new two-dimensional material and has been applied in many fields. With simple method of hydrothermal and high temperature calcination, nanostructured Ni/Ti3C2Tx hybrid was synthesized. The stable layer structure of Ti3C2 MXene providing high surface area as well as excellent electronic conductivity are beneficial for deposition and decomposition of discharge product Li2O2. Furthermore, possessing special catalytic activity, Ni nanoparticles with size of about 20 nm could accelerate Li2O2 breaking down. Taking advantage of two kinds of materials, Ni/Ti3C2Tx hybrid as cathode of Li-O2 battery can achieve a maximal specific capacity of 20,264 mAh/g in 100 mA/g and 10,699 mAh/g in 500 mA/g at the first cycle. This work confirms that the prepared Ni/Ti3C2Tx hybrid exhibiting better cycling stability points out a new guideline to improve the electrochemical performance of lithium-oxygen batteries.

Aqueous-phase oxygen evolution reaction (OER) is the bottleneck of water splitting. The formation of the O-O bond involves the generation of paramagnetic oxygen molecules from the diamagnetic hydroxides. The spin configurations might play an important role in aqueous-phase molecular electrocatalysis. However, spintronic electrocatalysis is almost an uncultivated land for the exploration of the oxygen molecular catalysis process. Herein, we present a novel magnetic Fe

Regulating the structure and morphology of discharge product is one of the key points for developing high performance Li-O

Two-dimensional MXene with high conductivity has metastable Ti atoms and inert functional groups on the surface, greatly limiting application in surface-related electrocatalytic reactions. A surface-functionalized nitrogen-doped two-dimensional TiO

Due to the advantages of rich resources, low cost, high energy conversion efficiency, long cycle life, and low maintenance fee, sodium–ion batteries have been regarded as a promising energy storage technology. However, their relatively low energy density compared with the commercialized lithium–ion batteries still impedes their application for power systems. Anode–free rechargeable sodium–metal batteries (AFSMBs) pose a solution to boost energy density and tackle the safety problems of metal batteries. At present, researchers still lack a comprehensive understanding of the anode-free cells in terms of electrolytes, solid–electrolyte interphase (SEI), and current collectors. This review is devoted to the field of AFSMBs, and outlines the breakthroughs that have been accomplished along with our perspective on the direction of future development for AFSMBs and the areas that warrant further investigation.

The topological structure of carbon materials for lithium storage performance is an active issue in energy resources. However, the low specific capacity of carbon materials limits their application in the rapidly developing market, although they have the highest marginal value. Herein, we develop a facile method for scaled-up production of materials with atomically dispersed metal sites anchored on nitrogen-enriched carbon nanosheets (M–N–C), including nickel, iron and manganese metal sites. This is the first time that low-cost atomically dispersed M–N–C has been used to enhance Li storage performance. The anchoring of the atomically dispersed metal sites effectively improves the extent of carbonization and optimizes the electronic structure, which enhances the conductivity and accelerates the adsorption kinetics for Li+; this results in high capacity and superior rate performance. In the case of Mn–N–C, it presents an ultrahigh specific capacity of 500 mA h g−1 at 1 A g−1 after 1000 cycles. The atomically dispersed materials also demonstrate satisfactory rate performance, with an extremely high specific capacity of 328 mA h g−1 at 10 A g−1; this is greatly superior to that of N-doped carbon nanosheets (

The new material Polypyrrole-Mo3S13 (abbr. Mo3S13-Ppy) is a new material prepared by ion-exchange between Ppy-NO3 and (NH4)2Mo3S13. The Mo3S13-Ppy was designed to exhibit strong selectivity for Ag+ and highly toxic Hg2+ in mixtures with other ions. It displays an apparent selectivity ranking of Hg2+ > Ag+ ≥ Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+. The strong affinity of Mo3S13-Ppy for Ag+ and Hg2+ was confirmed with extremely high distribution coefficients (Kd) (∼107 mL/g) and remarkable removal efficiencies (>99.99%), resulting in

Two-dimensional MXene, a significant member of the two-dimensional family, has attracted much interest in physics, energy evolution, environmental science, and nanomedicine. However, the acute toxi...

We develop a facile method to prepare a hierarchical mesoporous nanocomposite of manganese carbodiimide nanoparticles modified with N-doping carbon materials (MnNCN/NC). The nanocomposite is endowe...

LaSrNiO nanoparticles with different doping amount of strontium are synthesized through sol-gel method accompanied by high-temperature calcination. With the increase of Sr content, the crystal structure of samples changes from perovskite to spinel phase that promote both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) property. As a cathode catalyst for Li-O2 battery, LaSrNiO nanoparticles show a capacity performance of 9000 mAh·g−1 and significantly enhanced cyclability. The improved battery performance with Sr-doped nanoparticles can be ascribed to the high surface area of Sr-doped LaSrNiO nanoparticles combined with mixed spinel and perovskite phased structure which facilitate specific capacity and OER performance obviously. This research work is believed to shed light on a new thought to boost the performance of Li-O2 battery.

Nanocomposites of CoNi alloy nanoparticles loaded on Ketjenblack carbon (CoNi/KB) are successfully prepared through one-pot thermal decomposition of organic precursor solution. It can be proved, through a serious of characterization methods, that the introduction of porous carbon nanospheres with high specific surface area effectively prevents the serious agglomeration and oxidation of alloy nanoparticles. Highly dispersed CoNi alloy nanoparticles are evenly distributed on the surface of carbon nanospheres with a size of about ca. 5 nm. The CoNi/carbon nanosphere composites exhibit excellent electromagnetic wave absorbability when the doping mass is merely 15 wt% with the minimum reflection loss of −39.5 dB at 12.4 GHz and the effective absorption bandwidth (

The design of low-cost yet high-efficiency electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) over a wide pH range is highly challenging. We now report a hierarchical co-assembly of interacting MoS2 and Co9S8 nanosheets attached on Ni3S2 nanorod arrays which are supported on nickel foam (NF). This tiered structure endows high performance toward HER and OER over a very broad pH range. By adjusting the molar ratio of the Co:Mo precursors, we have created CoMoNiS-NF- xy composites ( x: y means Co:Mo molar ratios ranging from 5:1 to 1:3) with controllable morphology and composition. The three-dimensional composites have an abundance of active sites capable of universal pH catalytic HER and OER activity. The CoMoNiS-NF-31 demonstrates the best electrocatalytic activity, giving ultralow overpotentials (113, 103, and 117 mV for HER and 166, 228, and 405 mV for OER) to achieve a current density of 10 mA cm-2 in alkaline, acidic, and neutral electrolytes, respectively. It also shows a remarkable balance between electrocatalytic activity and stability. Based on the distinguished catalytic performance of CoMoNiS-NF-31 toward HER and OER, we demonstrate a two-electrode electrolyzer performing water electrolysis over a wide pH range, with low cell voltages of 1.54, 1.45, and 1.80 V at 10 mA cm-2 in alkaline, acidic, and neutral media, respectively. First-principles calculations suggest that the high OER activity arises from electron transfer from Co9S8 to MoS2 at the interface, which alters the binding energies of adsorbed species and decreases overpotentials. Our results demonstrate that hierarchical metal sulfides can serve as highly efficient all-pH (pH = 0-14) electrocatalysts for overall water splitting.

Li–oxygen batteries (LOBs) have drawn widespread attention in the past decades. Herein, bifunctional hybrid catalysts based on perovskite La0.5Sr0.5CoO3−δ with Ti3C2Tx MXene nanosheets have been pr...

The development of highly effective, universal, and economical electrocatalysts for hydrogen evolution reaction (HER) via structure modulations remains a great challenge. Herein, we propose a novel solidoid nitridation reduction method to synthesize α-MoC1–x quantum dots encapsulated in nitrogen-doped carbon (α-MoC1–x/NC) with a shape like “frog eggs”. Carbon nitride was first prepared by pyrolysis of urea and then mixed with ammonium molybdate tetrahydrate under a temperature-programmed reduction. With the assistance of nitrogen release during thermal treatment, N doping and an ultrathin porous structure were obtained. Benefiting from the strong interaction of α-MoC1–x quantum dots and nitrogen-doped carbon, the α-MoC1–x/NC delivered an outstanding performance toward HER at all pH values. Here, 118 mV, a lower overpotential, is needed to reach 10 mA cm–2 in alkaline solution, and the current density of α-MoC1–x grew much faster than the commercial Pt/C with increased potential. And, this can keep steadil...

The development of novel and highly efficient bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an ongoing challenge. The Cr3+ cati...

Lithium oxygen (Li-O

Ultrathin two-dimensional metal–organic frameworks (2D MOFs) have the potential to improve the performance of Li–O2 batteries with high O2 accessibility, open catalytic active sites, and large surface areas. To obtain highly efficient cathode catalysts for aprotic Li–O2 batteries, a facile ultrasonicated method has been developed to synthesize three kinds of 2D MOFs (2D Co-MOF, Ni-MOF, and Mn-MOF). Contributing from the inherent open active sites of the Mn–O framework, the discharge specific capacity of 9464 mAh g–1 is achieved with the 2D Mn-MOF cathode, higher than those of the 2D Co-MOF and Ni-MOF cathodes. During the cycling test, the 2D Mn-MOF cathode stably operates more than 200 cycles at 100 mA g–1 with a curtailed discharge capacity of 1000 mAh g–1, quite longer than those of others. According to further electrochemical analysis, we observe that the 2D Mn-MOF outperforms 2D Ni-MOF and Co-MOF due to a superior oxygen reduction reactions and oxygen evolution reactions activity, in particular, the e...

The development of high-performance, low-cost, and long-lasting electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is urgently needed for effective electrochemical water splitting. In the present study, an engineering process was employed to prepare "Lewis base-hungry" amorphous-crystalline nickel borate-nickel sulfide (Ni3(BO3)2-Ni3S2) heterostructures, which exhibited unprecedentedly high electrocatalytic activity toward both OER and HER in alkaline media. The optimal Ni3(BO3)2-Ni3S2/nickel foam (Ni3(BO3)2-Ni3S2/NF) electrode displayed an ultralow overpotential of only -92 and +217 mV to reach the current density of 10 mA cm-2 for HER and OER, respectively. When the Ni3(BO3)2-Ni3S2/NF electrode was used as both the anode and cathode for overall water splitting, a low cell voltage of 1.49 V was needed to achieve the current density of 10 mA cm-2, which was superior to the performance of most noble metal-free electrocatalysts. Results from density functional theory calculations showed that the Lewis base-hungry sites in the heterostructures effectively enhanced the chemisorption of hydrogen and oxygen intermediates, a critical step in HER and OER electrocatalysis. Results from this study highlight the significance of rational design and engineering of heterostructured materials for the development of high-efficiency electrocatalysts.

Defect engineering is an important approach to enhancing the catalytic activity of a material, but there have been few reported controllable experiments due to the lack of systematic and comprehensive understanding of the effects of defects. For nanocarbon catalysts, it is still a challenge to prepare both atom-doped and defect-engineered catalysts with the desired more effective active centers, which requires an in-depth understanding of both experiment and theory. Herein, a topological rich-vacancy-defect nitrogen-doped nanocarbon (TRNC) material is constructed in situ via a simple magnesiothermic technology. It exhibits remarkable oxygen catalytic performance, which can be compared to the best metal-free bifunctional carbon electrocatalysts reported, even better than that of commercial noble-metal RuO2. Combined with density functional theory (DFT) calculations, the carbon vacancy defects with edge nitrogen doping as intrinsic active sites were found to exhibit excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity. When used practically as a catalyst in Li–O2 batteries, with a capacity restriction of 500 mA h g−1, it displays a long cycling and high rate durability of over 300 cycles at 200 mA g−1. This excellent performance arises from the three-dimensional topological rich-vacancy-defect nitrogen-doped nanocarbon. The effects of vacancy sites and nitrogen doping were probed via first-principles simulations to clarify the catalytic mechanisms which contribute to this superior performance.

NiFe layered double hydroxides (NiFe-LDHs) have been regarded as significant electrocatalysts for the oxygen evolution reaction (OER). However, their overpotential must still be further reduced to enable commercial applications. Herein, a promising and highly effective "hydroxyl ions hungry" electrode structure was prepared for the first time via a two-step hydrothermal reaction procedure to enhance the surface adsorption kinetics to obtain an ultralow overpotential. The electrode exhibits OER activity with ultralow overpotentials of 203 mV and 293 mV at the current densities of 10 mA cm-2 and 100 mA cm-2, respectively, in 1.0 M KOH. These results reveal an important way to improve the catalytic performance in an alkaline medium.

Hollow PdO-Co3O4 nano-dodecahedrons with moderate catalytic activity were designed as electrocatalysts for Li-O2 batteries, and not only reduce the overpotentials effectively but also improve the reversibility of the ORR and OER, and cycle for more than 90 cycles stably with extremely low overpotentials.

A series of solid and macroporous N-doped carbon nanofibers composed of Fe3C nanoparticles (named as solid Fe3C/N-C NFs, solid Fe3C/N-C NFs-1, solid Fe3C/N-C NFs-2, macroporous Fe3C/N-C NFs, macroporous Fe3C/N-C NFs-1 and macroporous Fe3C/N-C NFs-2, respectively) were prepared through carbonization of as-electrospun nanofiber precursors. The results show that the magnetic Fe3C nanoparticles (NPs) dispersed homogeneously on the N-doped carbon fibers; as-prepared six materials exhibit excellent microwave absorption with a lower filler content in comparison with other magnetic carbon hybrid nanocomposites in related literatures. Particularly, the solid Fe3C/N-C NFs have an optimal reflection loss value (RL) of −33.4 dB at 7.6 GHz. For solid Fe3C/N-C NFs-2, the effective absorption bandwidth (EAB) at RL value below −10 dB can be up to 6.2 GHz at 2 mm. The macroporous Fe3C/N-C NFs have a broadband absorption area of 4.8 GHz at 3 mm. The EAB can be obtained in the 3.6–18.0 GHz frequency for the thickness of absorber layer between 2 and 6 mm. These Fe3C–based nanocomposites can be promising as lightweight, effective and low-metal content microwave absorption materials in 1–18 GHz.