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Background: To figure out the clinical meaning of serum trimethylamine oxide (TMAO), N-terminal-pro-brain natriuretic peptide (NT-proBNP) and hypoxia-inducible factor-1a (HIF-1a) with left ventricular function and pregnancy outcome in patients with pregnancy-induced hypertension. Methods: From January 2018 to October 2020, 117 patients with gestational hypertension were taken as the research objects and grouped into the gestational hypertension (pregnancy-induced hypertension, 55 cases), mild preeclampsia (mild PE, 43 cases) and severe preeclampsia (severe PE, 19 cases) in the light of the severity of the disease. Analysis of the relation of serum TMAO, NT-proBNP and HIF-1a with the severity of disease and cardiac function indexes in patients with gestational hypertension was conducted. All patients were followed up to the end of pregnancy, and the predictive value of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome in patients was analyzed. Results: Serum TMAO and NT-proBNP of patients were elevated, while HIF-1a was reduced with the severity of the disease (P < 0.05). Serum TMAO and NT-proBNP in patients with gestational hypertension were positively correlated but HIF-1a was negatively correlated with the severity of the disease (P < 0.05). Left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were elevated in gestational hypertension patients, while ejection fraction (LVEF) was reduced with the severity of disease (P < 0.05). Serum TMAO, NT-proBNP and HIF1a were associated with LVEDV, LVESV and LVEF values in patients with gestational hypertension (P < 0.05). Serum TMAO and NT-proBNP were elevated but HIF-1a was reduced in patients with a poor pregnancy outcome (P < 0.05). The AUC of the combined detection of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome was greater (P < 0.05). Conclusions: Serum TMAO, NT-proBNP and HIF-1a in patients with gestational hypertension are associated with disease severity and cardiac function, and have predictive and evaluative values for disease severity and pregnancy outcome.

The electrochemical CO

The selectivity of electrochemical reduction of CO2 to CO can be effectively improved by doping Sn into a CuAg film.

Electrochemical water splitting is a promising method for the renewable production of high-purity hydrogen via the hydrogen evolution reaction (HER). Ni-Fe layered double hydroxides (Ni-Fe LDHs) are highly efficient materials for mediating the oxygen evolution reaction (OER), a half-reaction for water splitting at the anode, but LDHs typically display poor HER performance. Here, we report the preparation of self-organized Ag@NiFe layered double hydroxide core-shell electrodes on Ni foam (Ag@NiFe/NF) prepared by galvanic etching for mediating both the HER and OER (bifunctional water-splitting electrocatalysis). This synthetic strategy allowed for the preparation of organized hierarchical architectures which displayed improved the electrochemical performance by tuning the electronic structure of the catalyst and increasing the surface area utilization. X-ray photoelectron spectroscopy (XPS) and theoretical calculations revealed that electron transfer from the Ni-Fe LDH to Ag influenced the adsorption of the reaction intermediates leading to enhanced catalytic activity. The Ag@NiFe/NF electrode displayed overpotentials as low as 180 and 80 mV for oxygen and hydrogen evolution, respectively, at a current density of 10 mA cm-2, and improvements in the specific activity by ∼5× and ∼1.5× for the oxygen and hydrogen evolution reaction, respectively, compared to benchmark NiFe hydroxide materials. Additionally, an integrated water-splitting electrolyzer electrode can be driven by an AA battery.

Metallic phase molybdenum disulfides exhibit impressive charge transfer ability and this has made them interesting candidates for use in the field of nano-science and heterogeneous catalysis. However, the synthesis of 100% pure bare 1T-MoS2 is difficult due to its kinetic instability. In the past, the phase transition mechanism from a semiconductor (2H) to a metallic (1T) phase has been explained only by theoretical calculations. Herein, we used magnetron sputtering to deposit a series of MoS2 films containing various metal heteroatoms as the dopants. Density functional theory (DFT) calculations revealed that the single-doped Cu-MoS2, Au-MoS2, Ag-MoS2, and Al-MoS2 exhibited distinct phase transitions compared to Cr-MoS2, Hf-MoS2, Ta-MoS2, and Zr-MoS2, due to the introduction of additional charge. Furthermore, the hydrogen evolution reaction (HER) activities of the series of MoS2 films were explored, and the adsorption free energy of H atoms was evaluated by DFT calculations.

Aqueous-based Zn–air and Al–air batteries are considered to be promising post-lithium energy storage technologies owing to their safety, environmental friendliness, affordability, and high energy density. Nevertheless, traditional liquid Zn–air and Al–air batteries have problems such as volatilization and leakage, as well as the realization of miniaturized, portable, and wearable electronic devices. The practice of optimizing the battery structure by replacing the flowing electrolyte with a solid type has emerged and made significant progress in the past ten years. Herein, this review provides a guiding and comprehensive summary of the basic understanding and manufacturing ideas of the solid electrolyte for Zn–air and Al–air batteries. First, two types of alkaline solid electrolytes are distinguished, including alkaline anion exchange membranes (AAEMs) and gel polymer electrolytes (GPEs). Then, three sorts of major framework materials (i.e., artificial organic polymer, biomass materials, and inorganic materials) are reviewed and discussed. Most importantly, the latest research progress and improvement strategies to enhance the electrolyte membrane performances involving conductivity, mechanical properties, and electrochemical stability are also highlighted. Finally, challenges and prospects for the future development of alkaline solid electrolytes are emphasized.

Background: To verify the validity and feasibility of using a mechanical compression method to locate the atrioventricular node in open-heart surgery. Methods: Ten healthy miniature pigs were used to establish an animal model of the beating heart under cardiopulmonary bypass. During the operation, the atrioventricular node and its surrounding areas were stimulated by mechanical compression (mechanical compression method), and the occurrence of complete atrioventricular block was judged by real-time electrocardiograph monitoring and direct observation of the heart rhythm to identify the position of the atrioventricular node. The final localization of the atrioventricular node was determined using the iodine staining method, and the results were used as the "gold standard" to test the effectiveness and feasibility of the mechanical compression method for locating the atrioventricular node. Results: With the beating heart model, complete atrioventricular block occurred after mechanical compression of the "atrioventricular node" area in 10 pigs. Nine pigs regained normal conduction immediately after the compression was released, and one pig failed to recover. No atrioventricular block or other arrhythmias occurred after mechanical compression of the "non-atrioventricular node" area. The sensitivity of the method was 86.6%, specificity was 100.0%, misdiagnosis rate was 0.0%, missed diagnosis rate was 13.4%, positive predictive value was 100.0%, negative predictive value was 97.9%, positive likelihood ratios were +∞, negative likelihood ratios were 13.4%, accuracy was 98.1%, and diagnostic odds ratio was +∞. Conclusion: This study innovatively proposes the application of the mechanical compression method to locate the atrioventricular node during operation and preliminarily proves that this method is effective and feasible through animal experiments.

The application of lithium metal anode with high specific capacity and energy density is limited by the volume expansion and pulverization caused by dendrite growth during cycle process. We propose a composite lithium anode by immersing molten lithium on the flexible three-dimensional (3D) carbon cloth scaffold with the zinc nanoparticles. The lithiophilic zinc nanoparticles layer of framework is synthesized by fast and easy electrochemical deposition from ionic liquid avoiding high temperature, high pressure and toxic reagent. The lithium is infused into the 3D lithiophilic framework, the composite anode is obtained. The steady network structure can confine the lithium and lead to Li dendrite restraining and reducing volume change due to the low interfacial resistance and reduce the effective current density, which induced the homogeneous Li growth. Benefiting from this, the Li infused 3D carbon cloth-Zn symmetric battery exhibits a low stripping/plating overpotential (~30 mV) and can be stable over 900 h at 1 mA cm−2. The Li//LiFePO4 battery delivers higher reversible capacity (140 mAh g−1 at 2 C and 120 mAh g−1 at 5 C) and stable cycling for 1500 and 2000 cycles than bare Li.

Here we prepare a hexagonal boron nitride (h-BN)–polyethylene oxide composite polymer electrolyte via a convenient casting method, which shows high mechanical strength. Meanwhile, the electrochemical properties (electrochemical window and lithium ion transference number) are enhanced but the ionic conductivity of the h-BN composite electrolyte is decreased after adding h-BN. Density functional theory (DFT) calculation results show that a stronger binding effect is observed between TFSI− and BN, compared to that between Li+ and BN. Molecular dynamics (MD) simulations are also utilized to study the mechanism behind the enhanced Li ion diffusion by h-BN addition. Li+ diffusion in PEO/LiTFSI/BN is lower than that in the PEO/LiTFSI system, but the diffusion of TFSI− exhibits a more significant decline rate in the presence of BN. This indicates that the presence of BN suppresses anion motion and enhances selectivity in Li+ transport. Thus, the PEO/LiTFSI/h-BN composite electrolyte exhibits higher Li ion conductivity but lower anion diffusivity than the PEO/LiTFSI system. Hence the h-BN composite polymer electrolyte in a Li/Li symmetric battery provides a long cycling time of 430 h at 0.2 mA cm−2. A Li metal/LiFePO4 full battery with the PEO/LiTFSI/h-BN composite electrolyte also works more efficiently for long-term cycling (140 cycles) than a filler-free PEO based electrolyte (39 cycles).

Defect and interface engineering is a powerful strategy to tune the electronic structure and adsorption behavior of electrocatalysts, boosting the performance of the electrocatalytic CO2 reduction reaction (eCO2RR). Herein, we construct a hybrid electrocatalyst, Bi2S3–Bi2O3@rGO, with a large amount of defects (oxygen vacancies etc.) and a specific interface between bismuth sulfide (Bi2S3) and bismuth oxide (Bi2O3) by a partial precipitation conversion method. Both experimental results and theoretical calculations reveal that the Bi2S3–Bi2O3 interface drastically lowers the formation energy of HCOO*, in favor of the production of formate (HCOOH) over CO, promoting the conversion of CO2 to HCOOH. The as-prepared electrocatalyst shows excellent electrocatalytic activity to generate HCOOH with a high faradaic efficiency of over 90% and a low overpotential of 700 mV, as well as excellent durability for more than 24 h.

Metallic 1T-phase MoS2 is considered to be the ideal electrocatalyst to carry out hydrogen evolution reaction (HER) because of favorable conductivity and sufficient active site compared with 2H-pha...

Unicornuate uterus has a low incidence,it is a congenital uterine developmental anomaly, it has many complications during pregnancy, and it is less common in pregnancy to term. This article retrospectively analyzes a case of unicornuate uterus with a full-term vaginal trial of labor and delivery with placental abruption resulting in neonatal asphyxia. We also present the typology of unicornuate uterus, diagnosis, and discuss the mode of delivery in the light of the literature, in order to raise awareness of this type of disease among medical professionals and reduce the occurrence of adverse pregnancy outcomes.

An increasing number of studies have focused on the relationship between neighbourhood environment and depressive symptoms among older people. However, the underlying mechanisms are still unclear. This study examined the association between neighbourhood environment and depressive symptoms among older urban Chinese adults and the mediator role of social capital in this association. Using a quota sampling approach, 472 respondents aged 60 years or older were recruited from 23 urban communities of Shanghai, China, in 2020. Depressive symptoms were measured with the Center for Epidemiologic Studies Depression Scale. Social capital was measured by two latent constructs: cognitive social capital (e.g., trust, reciprocity, belongingness) and structural social capital (e.g., memberships, social participation). Perceived physical neighbourhood environment was assessed in terms of health care, security, and public transportation status. Structural equation modelling was conducted to test the study hypotheses. Health care services in the community had a direct effect on depressive symptoms (β = -0.097, p < .05). Cognitive social capital played a mediator role in the relationship between physical neighbourhood environment and depressive symptoms (community health care: β = -0.124, p < .01; community security: β = -0.284, p < .01). The mediator effect of structural social capital in the relationship between physical neighbourhood environment and depressive symptoms was not significant. The findings highlight the role of physical neighbourhood environment in fostering community-based social capital and promoting mental health among older adults in urban China. Policy strategies could focus on improving community health care and security to promote mental health.

CoMoPx-based electrocatalysts are promising for hydrogen evolution reaction (HER) but suffer from high overpotential and poor stability at large current density. Herein, we propose CoMoP@NF in lower valence states by thorough phosphorization which improves the adhesion of the catalysts on substrate and facilitates the Volmer step. The CoMoP@NF can reach 39 mV at 10 mA cm−2, 119 mV at 100 mA cm−2, and a low Tafel slope of 73.3 mV per decade. The decline of i-t test in 10 h at ~370 mA cm−2 is only 1 mA cm−2. Theoretical calculations confirm the rational design of CoMoP whose Δ G H ∗ is as low as 0.15 and −0.01 eV corresponding to (013) and (211) facets, respectively. Electrons transfer from Co to Mo results in middle d band center of CoMoP that promotes H adsorption and desorption. This concept could provide valuable insights into the design of other catalysts for HER and beyond.

Preparing high-efficiency electrocatalyst through facile, low energy consumptive, and time-effective strategy is essential to the hydrogen generation via water electrolysis. Here, we report a galvanic replacement-mediated synthesis of highly active Co–Fe layered double hydroxides (Co–Fe LDHs) at room temperature as advanced electrocatalyst for water oxidation. The disc-like Co precursors were the first proposed as self-sacrificing templates for Co–Fe LDHs. By steady control of the carving of iron ions, the disc-like Co precursors are carved relaxedly and then formed to nanosheet-constructed Co–Fe LDHs. The Fe (II) ion is proved to a more preferable iron precursor than Fe (III) ion for Co–Fe LDHs nanosheets growth, owing to the “slow-growth” process. This catalyst shows a highly electrocatalytic activity towards the OER with low overpotential (η10 mA cm -2 = 270 mV), low Tafel slope (48.7 mV dec-1), and remarkable long-time stability.

Although NiFe-based (oxy)hydroxides species have been recognized as one of the most promising water oxidation catalysts, existing synthetic methods are difficult to fulfill the requirements of catalytic performance, lifetime and large-scale production. Here, we develop a scaled-up and simple dual-oxidative etching strategy for introducing metallic copper into a NiFe hydroxide nanosheet array on a Ni foam electrode (Cu–NiFe LDH/NF) for the oxygen evolution reaction. This dual-oxidation strategy is achieved via a galvanic–corrosion reaction between the metallic Ni template and ions with higher reduction potential (Fe3+ and Cu2+). The as-prepared electrode exhibits unparalleled activity toward water oxidation with an overpotential of 185 mV at a current density of 10 mA cm−2 and Tafel slope of merely 30 mV dec−1, respectively. More importantly, this inexpensive and simple manufacturing technique affords the Cu–NiFe LDH/NF electrode excellent activity retention for over 1200 hours.

In this study, we report a two dimensional network through the combination of CoO nanoparticles and nitrogen doped carbon nanotubes (CoO-NCNTs) derived from a lamellar coordination polymer, ([CoII(2,3-chedc)(DABCO)0.5]), (2,3-chedc, cyclohexene-2,3-dicarboxylate; DABCO, 1,4-diazabicyclo[2.2.2]octane). During the pyrolysis of this two dimensional metal–organic framework (MOF), the NCNTs emerge accompanied with the catalysis of CoO nanoparticles and are connected to form two dimensional networks. The cobalt oxide particles are encapsulated and remain at the apical position of NCNTs. Due to the specific architecture and high content of CoO in the composite, it possesses great potential for lithium/sodium storage. Noticeably, high capacity and super long calendar life of 2000 cycles with only 0.0063% capacity loss per cycle is acquired for Li storage at a current density of 500 mA g−1. In addition, it also exhibits good sodium storage performance, which delivers a high capacity of 450 mA h g−1, and long cycling capability for 300 cycles with a capacity loss of 0.066% at a rate of 500 mA g−1. Remarkable performance emphasizes the great potential of the two dimensional MOFs for extensive utilizations in energy storage and transfer processes.

The hydrogen evolution reaction (HER) is a promising clean and renewable energy source. Thus, efficient and inexpensive electrocatalysts for the HER have attracted considerable attention. Here, we report a two-step method for the synthesis of a unique CoMoO4–Co2Mo3O8 heterostructure. The CoMoO4–Co2Mo3O8 heterostructure exhibited superior HER activity that included a low overpotential of 57 mV, a Tafel slope of 55 mV dec−1 in a 1 M KOH solution, and excellent long-term stability given its high intrinsic activity and superior conductivity. Density functional theory calculations indicated that CoMoO4 and Co2Mo3O8 synergistically optimized electron distribution to reduce hydrogen adsorption energy and significantly enhance electrocatalytic activity. Our work may provide novel ideas for improving the HER performance of valence-rich transition element oxides.

Lithium-sulfur (Li-S) cells have received particular attention as a “post lithium ion” energy storage system. However, low sulfur utilization and poor redox kinetics are still key challenges to improving cycling efficiency. Herein, we develop a multi-functional polysulfide mediator based on carbon hollow nanospheres supported titanium nitride (C@TiN) dual-shell hollow nanospheres, in which the physical confinement, chemical adsorption, and catalysis for sulfur species conversion were successfully achieved simultaneously. As a result, C@TiN-S composites (approximately 70 wt% sulfur content) exhibit faster reaction kinetics and a higher polysulfide trap capability than that of C@TiO2-S composites when used as cathode materials in Li-S batteries. The C@TiN-S electrode delivers a reversible capacity of 453 mA h g−1, coupled with a high average Coulombic Efficiency (~ 99.0%). There is also limited capacitance decay (only 0.0033% per cycle), at a current density of 3 C, over 300 cycles. In particular, when the sulfur loading is increased to 4.2 mg cm−2, the C@TiN-S electrode can provide a high capacity of 820 mA h g−1 over 150 cycles at 0.2 C. DFT calculations reveal that the long-chain Li2S8 tend to break down into two shorter chain segments due to the strong interaction of TiN and LiPSs. Electrochemical analysis techniques indicate that TiN can effectively catalyze the reduction of polysulfide and the oxidation of Li2S during discharge and charge processes, respectively. Our work offers a new strategy to develop high-performance Li-S batteries based on multi-functional mediators.

Exploiting high efficient non-noble metal catalysts with low-cost and good stability for oxygen reduction reaction (ORR) is vital for fuel cells and metal-air batteries. In this work, we successfully constructed a novel nanosheets-shaped NiCoO2 hierarchical structure supported on CMK-3 support (i.e., NiCoO2@CMK-3 composite) via a facile hydrothermal method. Electrochemical characterization results reveal that the as-prepared NiCoO2@CMK-3 composite exhibits remarkable ORR electrocatalytic activity with a positive peak potential of 0.81 V (vs. RHE), an onset potential of 0.90 V (vs. RHE), a high current density of 4.10 mA cm−2 at 0.4 V, and a nearly four-electron reduction pathway, which are comparable to the state-of-the-art Pt/C catalyst with the same mass. In addition, the NiCoO2@CMK-3 composite possesses excellent methanol-tolerance and electrochemical stability, which are better than Pt/C. The outstanding performance confirms the NiCoO2@CMK-3 composite as a promising efficient ORR catalyst in fuel cells and metal-air batteries.

The phase engineering of transition metal tellurides is a promising method for the regulation of chemical bonding and electronic configuration, which plays a significant role in the design of efficient catalysts for hydrogen evolution reactions. The metallic phase of MoTe2 has been reported to reveal prominent electrocatalytic performance over the semiconductor phase. The comprehensive first-principle calculations indicated that the depth charge transfer induced by the Co-Ni metallic bi-doping better facilitated the phase transition than those corresponding to specific mono-metallic doping. Based on the above principle, a series of Co and Ni co-doping MoTe2 (Co,Ni-MoTe2) nanofilms with different doping concentrations were successfully deposited by the magnetron sputtering technique. Under the synergistic effects of electron injection and strain, Co,Ni-MoTe2 possessed a considerable 1T’ phase. The Co,Ni-MoTe2 films exhibited a remarkable overpotential of 10 mA cm–2 for HER at –82 mV, and the active sites promoted catalytic performance as confirmed by the computational modeling.

In this paper, the unmanned aerial velhicle (UAV) path planning problem with obstacles is disscussed for an air-ground collaborative system which is composed of a messenger UAV and multiple unmanned ground vehicles (UGVs). The messenger UAV needs to visit each UGV to collect and share information. The aim of this problem is to achieve a shortest path which makes the UAV fly over all UGVs while avoiding obstacles. By the Dubins model, the path planning problem is formulated as a Dynamic Dubins Traveling Salesman Problem with Neighborhood (DDTSPN) under obstacle constraints. To adapt to the change of UGVs’ locations and reduce the complexity of tuning global path for obstacle avoidance, a moving horizon optimization strategy is porposed. After the UAV visits a UGV, the rest of UGVs’ access sequence and access locations are determined using SOM method according to the real-time locations of UGVs. Further, the DAPF algorithm is presented to replan the path which enters the obstacle regions. Simulation results show the advantages of the proposed path planning algorithm.

Hybrid materials with delicate composition and morphology usually promote advanced functions. We report a simple synthesis approach to coaxially grow MoS2 nanosheets on carbon nanotubes (CNTs), which were precoated with polydopamine (PDA), with the ability to readily control phase and morphology. It is found that the thin PDA layer on CNTs surface with abundant catechol base and chinone base can effectively attract both Mo4+ and S2– for subsequently in situ forming MoS2 shell and sheet-like morphology, and therefore, it is essential for the successful deposition of MoS2. The as-prepared MoS2 nanosheets/CNTs (MoS2@CNT) composite with a unique hierarchical hybrid nanostructure with large active surface and enhanced structural robustness has greatly promoted the charge-transfer process and enhanced the electrochemical properties when used as the electrode materials for lithium-ion batteries and sodium-ion batteries. As the anode materials for LIBs, the MoS2@CNTs electrode exhibited extremely stable cycling p...

We designed dielectric gels, a new type of polymer-based dielectric material. By using solvents with high dielectric constants, the gels achieve a unique combination of ultra-high dielectric constant, low elastic modulus, and excellent transparency, which are extremely challenging or impossible to realize with traditional polymer dielectrics. The gels exhibit high stretchability (stretch of approximately 10) and low mechanical hysteresis. We demonstrated the use of the dielectric gels by fabricating a bioinspired tunable lens, the focal length of which can be adjusted by varying the applied voltage. We believe that the dielectric gels, as a new type of polymer dielectric, offer new opportunities for soft robotics, sensors, electronics, optics, and biomimetics. Stretchy and see-through substances known as dielectric gels may find application in soft robotics due to their capabilities of controllable movement. Insulating membranes can be stimulated to squeeze like a muscle by applying voltage pulses. Shujiang Ding from Xi’an Jiaotong University, China, and co-workers have developed a material that reduces the typically high voltages needed for movement by 50% compared with a commercial membrane. They used ultraviolet polymerization to lock liquid molecules with high charge-storing properties within a hydrocarbon chain network, producing super-insulating gels that can be extended up to 10 times their original size without damage. A bioinspired lens was fabricated by sandwiching a liquid between two gel membranes. Voltage-tunable pressure from the gels squeezed the lens and changed its focal length, similar to the changes seen in the human eye when focusing. Dielectric gels, a new type of polymer-based dielectric material have been designed. The gels achieve a unique combination of ultra-high dielectric constant, low elastic modulus, and excellent transparency, which are extremely challenging or impossible to realize by traditional polymer dielectrics. We have demonstrated the use of the dielectric gel by fabricating a bioinspired tunable lens, the focal length of which can be adjusted by varying the applied voltage. Dielectric gels offer new opportunities for soft robotics, sensors, electronics, optics, and biomimetics.

The efficiency of energy storage technologies such as water splitting and metal-air batteries is limited by the sluggish dynamics of the oxygen evolution reaction (OER). Herein, we report a galvanic replacement-mediated method for in-situ growth of iron-nickel nitride on carbon nanotubes (CNTs) as a powdery catalyst for OER. This in-situ grown structure creates intimate interaction between the active substance of Fe2Ni2N and CNTs so as to accelerate charge transfer in the catalytical interface. First-principles calculations reveal that the Fe2Ni2N is intrinsically metallic, and the contribution mainly derives from the Fe atoms at corner sites of crystal structures. A good synergistic effect between metallic Fe2Ni2N with excellent intrinsic activity and conductive CNTs lead to outstanding electrochemical performance with a low overpotential (η10 mAcm-2 = 282 mV) and Tafel slope (38 mV dec−1), as well as good long-term stability.

NiCo2O4 nanoflowers were synthesized through a microwave-assisted hydrothermal method and used as a type support for Ni(OH)2 nanoparticles. In the three-dimensional NiCo2O4 nanoflowers, two-dimensional ultrathin nanosheets supported the Ni(OH)2 nanoparticles by homogeneous precipitation. The materials were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The electrochemical oxidation of methanol was probed through the NiCo2O4/Ni(OH)2 modification on a glassy carbon electrode in an alkaline medium by employing cyclic voltammetry (CV) and chronoamperometry (CA). The current density of the NiCo2O4/Ni(OH)2 electrode in 1 M KOH with 0.5 M methanol ascends to 92.3 A g−1 and restores to 94.6% of the primitive value through the replacement with a new solution after a long-term CV cycling (500 cycles). Therefore, the compounds further corroborate their excellent electrocatalytic activity and superb perennial stability for methanol oxidation. This study demonstrates that NiCo2O4/Ni(OH)2 is a peculiar material with an outstanding performance in direct methanol fuel cells.

Oxygen vacancy-enriched In2O3 nanomaterials are promising catalysts for electrocatalytic CO2 reduction owing to their excellent capability to activate CO2 during catalysis. Despite substantial progress, facile and controllable methods for oxygen vacancy construction require further exploration. Herein, magnetron sputtering is used for generating oxygen vacancies in In2O3 films with the help of high-energy plasma treatment. A series of In2O3 films were prepared through magnetron sputtering at different oxygen partial pressures, and the In2O3 sample without oxygen partial pressure exhibited excellent performance in HCOOH production. The large yield of C1 products is mainly attributed to the increased surface electronic density according to density functional theory (DFT) calculations. The DFT results indicated that the reaction proceeded with *COOH obtained as the intermediate, and the formation barrier of *COOH decreased with an increase in oxygen vacancies. The present route provided a novel and convenient strategy for developing defect-rich catalysts for electrochemical CO2RR.

It is of vital importance to develop novel low-cost and high-efficiency electrocatalysts towards oxygen reduction reaction (ORR), which play a considerable impact on electrochemical energy conversion and storage devices, such as fuel cells and metal-air batteries. In this work, we demonstrate a kind of highly active nitrogen-doped carbons with uniform hierarchical structures through sulfonated polystyrene regulating the distribution of PANI covering on CNTs, prepared by a reliable and controllable route. The as-prepared electrocatalyst shows outstanding activity towards ORR in alkaline media, manifesting comparable or even better performance compared to the commercial Pt/C. The optimized nitrogen-doped CNTs exhibits an onset potential (Eonset) of 0.94 V (vs. reversible hydrogen electrode (RHE)) and half-wave potential (E1/2) of 0.83 V (vs. RHE) in 0.1 M KOH with superior stability, durability and methanol tolerance, suggesting their promising applications in fuel cells and metal-air batteries. The significantly improved electrochemcal properties demonstrate the unique sulfonated polystyrene layer anchoring on the surface of CNTs in the as-designed PANI@CNTs-SPS contributes to uniform distribution of nitrogen sites of the catalyst.

Synthesis of novel bifunctional catalysts based on earth-abundant elements with high catalytic activities for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) becomes a main strategy to promote the development of metal-air batteries and fuel cells. Herein, a novel Co 2+ -based mixed transition metal oxide composite, the three-dimensional (3D) nanosheet-structured NiCoO 2 /carbon nanotubes (CNTs) composite, was successfully synthesized through a facile one-pot method. The better electrocatalytic activities of NiCoO 2 /CNTs for both ORR and OER than those of pure NiCoO 2 , CNTs, physically mixed NiCoO 2 and CNTs, and Co 3 O 4 /CNTs are proved. The comparison of local ORR and OER electrocatalytic activities of NiCoO 2 /CNTs to other catalysts are obtained by scanning electrochemical microscopy (SECM) characterizations. The closed oxygen reduction peak and half-wave potentials, nearly four-electron dominated process, better methanol tolerance and electrochemical stability confirm the comparable electrocatalytic performance and better stability of NiCoO 2 /CNTs to the commercial Pt/C catalyst for ORR. The similar stability of NiCoO 2 /CNTs demonstrates its comparable electrocatalytic performance to the state-of-the-art RuO 2 catalyst for OER. The as-prepared NiCoO 2 /CNTs composite presents as a promising bifunctional oxygen electrocatalyst in alkaline solution for potential applications.

Electrochemical water splitting is considered to be one of the most promising strategies for clean and efficient hydrogen production. In this paper, an in-situ growth of iron-nickel phosphide on nickel foam (FeNiPx/NF) is demonstrated as a self-supported ternary catalyst for electrochemical water splitting. The FeNiPx/NF were prepared by a thermo-reaction between NaH2PO2 and NiFe hydroxide precursors that are in situ grown on Ni foam via a simple chemical precipitation reaction. In this newly proposed method, the nickel foam not only acts as an electrode substrate, but also serves as a slow-release Ni source in the reaction due to its oxidation by Fe3+ in solution. Benefiting from collaborative advantages of bimetallic composite, metallic phosphide, and unique electrode fabrication, the FeNiPx/NF exhibits extraordinarily high activities for both OER and HER with low overpotentials of of 192 and 106 mV at 10 mA cm−2, 236 and 161 mV at 100 mA cm−2, respectively. The voltage during the galvanostatic electrolysis is well maintained for almost 400 h without any visible elevation, representing the few most stable noble-metal-free catalysts for water splitting.

A highly active nitrogen-doped catalyst with a unique red-blood-cell (RBC) like structure is reported for oxygen reduction reaction (ORR). The catalyst Fe,N-C@carbon-900 was prepared by pyrolysis of the polyaniline (PANI) and polystyrene (PS) composites with adsorption of ferric ion on the shell of sphere structure at 900 °C. Fe,N-C@carbon-900 with a unique RBC-like structure provides plenty of catalytic sites combining the electrical conductivity of the carbon sphere with the catalytic activity of the nitrogen-doped layer. The four-electron reduction pathway is selected for the catalyst Fe,N-C@carbon-900. The catalyst exhibit the ORR E onset at 0.87 V (potentials is versus to reversible hydrogen electrode (RHE)), E 1/2 at 0.78 V and high diffusion-limiting current density (5.20 mA/cm 2 ). Furthermore, this work indicates that both N and Fe accounted for high activity of the catalyst Fe,N-C@carbon-900 toward the oxygen reduction process. It is concluded that Fe and N exhibit synergistically promotion in the ORR activity for the catalyst Fe,N-C@carbon-900. We also provide a rational design of electrocatalysts with high ORR activity to further clarify the essential ORR sites of heteroatom doped carbon materials for fuel cells and metal–air battery applications.

Carbon-based anode materials are faced with challenges in rechargeable sodium-ion batteries (SIBs). In this paper, we describe a substrate, N-doped amorphous micron-sized carbon ribbons (AMCRs), derived from biomass from raupo, on which few-layer MoS2 nanosheets with enlarged interlayer spacings (≈0.75 nm) are anchored. The nitrogen-enriched AMCRs are economically prepared by a single pyrolysis step. The uniform distribution of nitrogen atoms enables ultra homogeneous growth of the MoS2 nanosheets on the AMCRs. The as-prepared AMCRs@MoS2 composite is fabricated as an anode material for SIBs, and carboxymethylcellulose (CMC) and polyvinylidene fluoride (PVDF) are chosen as binders to mix the anode materials to compare their battery performance. The anode composite with CMC as the binder demonstrates an improved initial coulombic efficiency of 75.6%, a higher specific capacity (366 mA h g−1 at a current density of 1 A g−1) and a better cycling stability (305 mA h g−1 after 300 cycles). The anode material composed of few-layer MoS2 anchored on low-cost nitrogen-doped AMCRs with CMC as the binder can be a competing candidate for large-scale SIB production.

Electrochemical water splitting is considered to be one of the most promising strategies to produce hydrogen to ease the energy crisis. In this study, we demonstrate a galvanic-replacement mediated synthesis of copper-nickel bimetallic nitrides on partially sacrificial nickel foams (CuxNi4−xN/NF) as the direct catalytic electrode for hydrogen evolution reaction (HER). The Ni foam serves as not only the cathodic electrode substrate, but also the only Ni precursor for the CuxNi4−xN catalyst, which can be galvanically replaced by Cu(I) ion. The obtained CuxNi4−xN/NF exhibits an excellent electrocatalytic performance towards the HER in both acidic and alkaline media with a very low overpotential of ∼110 mV at a current density of 100 mA cm−2 in the 0.5 M H2SO4 and 1 M KOH solutions. The electrode presents a good long-term working stability, particularly reflecting in more than 65 h of consistent galvanostatic electrolysis in 0.5 M H2SO4. The CuNi bimetallic nitrides are intrinsically metallic, allowing for an enhanced charge transport and an excellent electrical conductivity. Combining the experimental result and the theoretical calculation further reveals that the electrocatalytic active sites primarily originate from nickel species.

For the first time, we design and synthesise a novel structure of hollow carbon nanosheets with MgAl-layered double hydroxide (MgAl-LDH) as the template and poly-dopamine (PDA) as the carbon source via a facile method. To reveal the significance of hollow carbon nanosheets, buffering large strains during the lithium de-intercalation cycle and prolonging the cycle life, SnO2@C nanocomposites as anode materials for lithium-ion batteries (LIBs) are prepared. As a result, the structure of hollow carbon nanosheets contributes to the improvement of the capacity and stability of the SnO2 anode material. The capacity of hollow SnO2@carbon nanosheets remains 693 mA h g−1 after 450 cycles with the current density of 0.5 A g−1 far better than that of pristine SnO2.

In this work, we developed a novel hierarchical hybrid nanostructure of reduced graphene oxide (rGO) supported cobalt-doped ZnO nanoparticles (Co-doped ZnO NPs@rGO) via a simple solution-refluxing strategy. The ultrafine CoZn-glycolate nanoparticles precursor was obtained from the alkoxide reaction among ethylene glycol and Co 2+ /Zn 2+ ions absorbed onto GO support. The post-annealing process makes the precursor easily transferred into crystalline Co-doped ZnO NPs@rGO with well-retained morphology and the oxidation state of Co element to be Co 2+ in the final hybrid. When evaluated as an oxygen reduction reaction (ORR) electrocatalyst in an O 2 -saturated 0.1 M KOH solution, the Co-doped ZnO NPs@rGO hybrid with the optimal Co-doping concentration of 0.38 ( i.e. , Co 0.38 Zn 0.62 O NPs@rGO) exhibits highly enhanced ORR electrocatalytic activity compared to the ZnO@rGO composite with an ORR peak potential of 0.74 V ( vs . RHE), an onset potential of 0.90 V, a current density of 3.94 mA cm −2 (at 0.4 V (vs. RHE)) and a nearly four-electron catalytic pathway. The good electrochemical stability and excellent methanol-tolerance capability of the resultant Co 0.38 Zn 0.62 O NPs@rGO hybrid, superior to those of the commercial Pt/C catalyst, further demonstrate its great potential as an efficient ORR electrocatalyst. This work proposes the feasibility of the semiconducting ZnO nanomaterials as novel ORR electrocatalysts via doping active oxygen catalytic element, such as Co 2+ , for the first time.