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Metal–nitrogen–carbon has attracted great research interest for sodium storage. However, the limited and unstable M–Nx active sites result in poor rate performance and inferior cycle life. Herein, CoFe nanoalloy clusters embedded into N-doped carbon nanofibers (denoted as CoFe–N–C) with hollow porous structures are designed. 3D conductive carbon networks increase electronic conductivity, and the interconnected hollow structures effectively suppress volume expansion during cycling. According to the theoretical calculations, the CoFe alloy nanoclusters serve as active sites that improve the electronegativity of N-doped carbon, thus providing suitable bonding energy for Na+ and facilitating Na+ diffusion. When applied in sodium-ion capacitors, such a CoFe–N–C anode can deliver a high capacity of 298 mA h g−1 at 1 A g−1 over 3000 cycles with nearly 100% capacity retention. The assembled sodium-ion capacitors with CoFe–N–C as the anode give a broad working voltage window (0–4.0 V), an outstanding energy density of 211.6 W h kg−1 at 200.0 W kg−1 and a superior power density of 20.0 kW kg−1 at 127.8 W h kg−1, together with a low capacity decay of 0.012% per cycle after 900 cycles. [ABSTRACT FROM AUTHOR]

Herein, a brush-like Cu2O–CoO core–shell nanoarray on copper foam (Cu2O–CoO/CF) can achieve efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance in alkaline seawater electrolyte. This Cu2O–CoO/CF shows overpotentials as low as 315 and 295 mV at 100 mA cm−2 for the OER and HER, respectively. Moreover, it could also be operated at 1.82 V with 100 mA cm−2 in a two-electrode electrolyzer and exhibits strong stability for at least 50 hours of electrolysis. The excellent performance and hierarchical structure advantages of Cu2O–CoO/CF provide new ideas for designing efficient seawater splitting electrocatalysts. [ABSTRACT FROM AUTHOR]

The use of large-current-density electrolysis of seawater is promising for a massive hydrogen (H2) production. This process, however, requires high-performance and cost-effective bifunctional catalysts for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Herein, a nickel–iron sulfide nanosheet array on nickel foam (NiFeS/NF) is demonstrated to be a superb bifunctional electrocatalyst for seawater splitting, delivering the industrially demanded current density of 500 mA cm−2 at overpotentials of 300 and 347 mV for OER and HER in alkaline seawater, respectively. Moreover, its corresponding two-electrode electrolyzer only requires a cell voltage of 1.85 V to drive 500 mA cm−2 and shows a strong stability for at least 50 h of electrolysis in alkaline seawater, outperforming the most recently reported seawater-splitting catalyst electrodes. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of nitrite (NO2−) is considered an effective method to solve its environmental pollution issue as well as sustainable ammonia (NH3) synthesis under ambient conditions but still requires high-performance catalysts. Herein, self-supported monoclinic WO2 nanoparticles with abundant oxygen vacancies (OVs) on a tungsten plate (WO2/W) are demonstrated as a highly efficient electrocatalyst for selectively reducing NO2− to NH3. In 0.1 M NaOH solution containing 0.1 M NO2−, such an electrocatalyst achieves an excellent yield of 14 964.25 ± 826.06 μg h−1 cm−2 and high faradaic efficiency (FE) of 94.32 ± 1.15% at −0.9 V. Remarkably, the assembled Zn–NO2− battery delivers a high power density of 5.05 mW cm−2 and simultaneously offers an abundant NH3 yield of 1923.88 μg h−1 cm−2. Theoretical calculations reveal the critical role of OVs for WO2 in the nitrite electrocatalytic reduction process and its possible reaction pathway. [ABSTRACT FROM AUTHOR]

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed. Interacting with human cells, smart biomaterials can play a key role in novel tissue morphogenesis. Various aspects of biomaterials utilized in or being sought for the goal of encouraging bone regeneration, skin graft engineering, and nerve conduits are discussed in this review. Beginning with bone, this study summarizes all the available bioceramics and materials along with their properties used singly or in conjunction with each other to create scaffolds for bone tissue engineering. A quick overview of the skin-based nanocomposite biomaterials possessing antibacterial properties for wound healing is outlined along with skin regeneration therapies using infrared radiation, electrospinning, and piezoelectricity, which aid in wound healing. Furthermore, a brief overview of bioengineered artificial skin grafts made of various natural and synthetic polymers has been presented. Finally, by examining the interactions between natural and synthetic-based biomaterials and the biological environment, their strengths and drawbacks for constructing peripheral nerve conduits are highlighted. The description of the preclinical outcome of nerve regeneration in injury healed with various natural-based conduits receives special attention. The organic and synthetic worlds collide at the interface of nanomaterials and biological systems, producing a new scientific field including nanomaterial design for tissue engineering. [ABSTRACT FROM AUTHOR]

A cell-laden tissue engineering scaffold for osteochondral integrated repair is one of the ideal strategies for osteochondral lesions. In this study, we fabricated cell-laden porous hydrogel scaffolds with gradient nano-hydroxyapatite using methacrylic anhydride gelatin (GelMA), nano-hydroxyapatite (nHA), and polyethylene oxide (PEO) solution for osteochondral tissue regeneration. The scaffold possessed interconnected pores and a nano-hydroxyapatite gradient in the vertical direction. The chemical, physical, mechanical, and biological properties of the hydrogel solutions and scaffolds were characterized. In vitro experiments confirmed that cells were distributed homogeneously and that different pore structures could affect the proliferation and differentiation of BMSCs. The Nonporous hydrogel was beneficial for the chondrogenic differentiation of BMSCs and interconnected pores were conducive to BMSC proliferation and osteogenic differentiation. The osteochondral integrative repair capacity of the scaffold was assessed by implanting the scaffolds into the intercondylar defect of the rabbit femur. By constructing pore structures in different layers, the cells in different layers of the hydrogels were in an intrinsic environment for survival and differentiation. Animal experiments confirmed that tissue engineering scaffolds for osteochondral lesions require different pore structures in different layers, and gradient structure facilitated integrated repair. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrite reduction not only holds significant potential in the control of nitrite contamination in the natural environment, but also is an attractive approach for sustainable ammonia synthesis. In this communication, we report that a TiO2−x nanobelt array with oxygen vacancies on a titanium plate is able to convert nitrite into ammonia with a high faradaic efficiency of 92.7% and a large yield of 7898 μg h−1 cm−2 in alkaline solution. This monolithic catalyst also shows high durability with the maintenance of its catalytic activity for 12 h. Theoretical calculations further reveal the critical role of oxygen vacancies in nitrite electroreduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of nitrite (NO2−) to ammonia (NH3) can simultaneously achieve wastewater treatment and ammonia production, but it needs efficient catalysts. Herein, Cu2O particles self-supported on Cu foam with enriched oxygen vacancies are developed to enable selective NO2− reduction to NH3, exhibiting a maximum NH3 yield rate of 7510.73 μg h−1 cm−2 and high faradaic efficiency of 94.21% at − 0.6 V in 0.1 M PBS containing 0.1 M NaNO2. Density functional theory calculations reveal the vital role of oxygen vacancies during the nitrite reduction process, as well as the reaction mechanisms and the potential limiting step involved. This work provides a new avenue to the rational design of Cu-based catalysts for NH3 electrosynthesis. [ABSTRACT FROM AUTHOR]

Electrocatalytic NO reduction controls NO emission and produces NH3 under ambient conditions. Herein, a NiO nanosheet array on titanium mesh is proposed as a highly active and selective electrocatalyst for NO reduction, attaining a faradaic efficiency of up to 90% with a NH3 yield of 2130 μg h−1 cm−2. Its aqueous Zn–NO battery can generate electricity with a power density of 0.88 mW cm−2 and simultaneously offer an NH3 yield of 228 μg h−1 cm−2. The NO electroreduction mechanism on NiO is revealed using theoretical calculations. [ABSTRACT FROM AUTHOR]

Ni–Cu alloy-based nanomaterials are representative cost-effective materials that have been widely used as highly active and stable electrocatalysts for electrochemical energy applications, such as the water oxidation reaction, the methanol/ethanol reaction and many other small molecule oxidation reactions. Here, novel short needle-like complex oxides of NixCu1−x/CuO/Ni(OH)2 are rationally designed and synthesized to further promote their oxygen evolution reaction (OER) performance. Under the tuning of electron perturbation and surface morphology, Ni0.7Cu0.3/CuO/Ni(OH)2 reached an optimum performance of ∼136.6 mVRHE kinetic potential and ∼160 mVRHE (vs. 3.33 A g−1) over-potential with a Tafel slope of 66 mV dec−1. Furthermore, the complex oxides are directly grown on glass carbon, which works as a binder-free and carbon-free electrode, leading to an excellent stability of 200 000 s with 39% activity loss. Due to the electron perturbation role of Cu as well as the synergistic interactions among Ni–Cu, CuO and Ni(OH)2, the obtained Ni0.7Cu0.3/CuO/Ni(OH)2 complex oxide is significantly more active and stable than those of NixCu1−x alloy, CuO and Ni(OH)2. Our results demonstrate a general strategy to design cost-efficient OER electrocatalysts by using a conventional and easily accessible Ni0.7Cu0.3/CuO/Ni(OH)2 hybrids to possibly replace commercial Ru/Ir-based materials. [ABSTRACT FROM AUTHOR]

Rational design and development of high-efficiency electrocatalytic materials made from earth-abundant elements for H2O2 generation via a two-electron O2 reduction reaction (2e− ORR) is of crucial significance but still challenging. Here, we demonstrate that CoTe nanoparticles embedded in a nitrogen-doped hollow carbon polyhedron (CoTe@NC) can be adopted as a highly selective and stable 2e− ORR electrocatalyst. Benefiting from the synergistic effect between the highly active CoTe nanoparticles and nitrogen-doped hollow carbon polyhedron, in 0.1 M HClO4, the CoTe@NC hybrid exhibits superb electrocatalytic activity toward the 2e− ORR with high selectivity of up to 92.6% and a large H2O2 production rate of 297.9 ppm h−1 at −0.044 V versus reversible hydrogen electrode. Moreover, it operates rather stably under the working conditions with a negligible current decrease after 12 h. Theoretical calculations further provide insight into the catalytic mechanism involved. [ABSTRACT FROM AUTHOR]

Electrosynthesis of NH3 from N2 addresses the need for renewable electricity storage and provides a promising alternative to the Haber–Bosch process. Unfortunately, it is hindered by sluggish kinetics and low faradaic efficiency (FE) due to the strong N≡N triple bond and competing proton reduction. Herein, we propose that the surface engineering of a CoP nanoarray supported on a titanium mesh using hydrophobic octadecanethiol (C18@CoP/TM) is an effective strategy to enhance the electrocatalytic activity of the CoP nanoarray supported on a titanium mesh for ambient N2-to-NH3 conversion. Such C18@CoP/TM offers an NH3 yield of 1.44 × 10−10 mol s−1 cm−2 and a FE of 14.03% in 0.1 M Na2SO4, surpassing its CoP/TM counterpart (0.783 × 10−10 mol s−1 cm−2, 5.83%). Moreover, C18@CoP/TM also shows steady NH3 yield and FE in a six-cycle test with high durability. Density functional theory calculations reveal that modifying CoP with a C18 layer leads to a regulated surface electronic structure, which further promotes the catalytic formation of NH3. [ABSTRACT FROM AUTHOR]

Advanced electrode materials embrace the key to the fundamental progress in rechargeable ion battery systems, which are essential to meet the finite nature of fossil fuels and the growing energy demands for clean and renewable energy. Metal phosphides in particular offer opportunities in rechargeable ion batteries owing to the extraordinarily high theoretical capacity and suitable redox potential. Notwithstanding these advantages, metal phosphides suffer from drastic volume variation during the electrochemical cycling process, resulting in relatively low capacity retention. Constructing metal phosphide–carbon heterostructures is an engrossing approach, which is because nanocarbon possesses bifunctional features that afford an electronic pathway and alleviate large volume expansion. Thus, the hybridization strategies of metal phosphides with different carbonaceous species are specifically highlighted in this review, followed by the illustration of how a robust understanding of these carbon matrixes within composites provides fundamental insights into the electronic conductivity, cycling durability, and rate capacity in metal phosphide electrodes. Meanwhile, the systematic discussion of the Li+/Na+/K+ ion storage mechanism in metal phosphides has also been expressly represented. Based on the insights, we outline the critical issues and challenges of metal phosphide/carbon heterostructures that need to be addressed to broaden their contribution in rechargeable ion batteries. [ABSTRACT FROM AUTHOR]

Recently, a two-dimensional Pma2-SiS monolayer has been predicted to show promising electronic properties [Nano Lett., 2015, 16, 1110]. However, it is suggested that Pma2-SiS is not suitable as an anode for Li-ion batteries [J. Power Sources, 2016, 331, 391]. By employing density functional theory calculations, we find that an ultrahigh theoretical specific capacity of 893.4 mA h g−1 can be achieved in Pma2-SiS due to the strong bonding between Li and the S atoms released from Si–S bond breakage. Additionally, the low barrier of Li-diffusion (0.08 eV) along the Si–Si bond direction and the moderate average voltage (1.12 V) of the Li intercalation suggest that Pma2-SiS is promising as an anode material for Li-ion battery applications. [ABSTRACT FROM AUTHOR]

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, C 3 N 5 -based materials have a major advantage over their carbon nitride (C x N y ) 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 C 3 N 5 -based materials in recent years, a comprehensive summary of the immediate parameters of this promising material is still lacking. Given the rapid development of C 3 N 5 -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 C 3 N 5 -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 C 3 N 5 -based materials for energy and environmental applications, thus offering researchers focussed on C x N y -materials an in-depth understanding of those based on C 3 N 5 . Finally, considering the limitations and deficiencies of C 3 N 5 -based materials, we have proposed enhancement schemes and strategies, while presenting personal perspectives on the challenges and future directions for C 3 N 5 . Our ultimate aim is to provide valuable insights for the research community in this field.

Herein, a brush-like Cu 2 O-CoO core-shell nanoarray on copper foam (Cu 2 O-CoO/CF) can achieve efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance in alkaline seawater electrolyte. This Cu 2 O-CoO/CF shows overpotentials as low as 315 and 295 mV at 100 mA cm -2 for the OER and HER, respectively. Moreover, it could also be operated at 1.82 V with 100 mA cm -2 in a two-electrode electrolyzer and exhibits strong stability for at least 50 hours of electrolysis. The excellent performance and hierarchical structure advantages of Cu 2 O-CoO/CF provide new ideas for designing efficient seawater splitting electrocatalysts.

There is an urgent need for the development of high performance electrocatalysts for the CO 2 reduction reaction (CO 2 RR) to address environmental issues such as global warming and achieve carbon neutral energy systems. In recent years, Cu-based electrocatalysts have attracted significant attention in this regard. The present review introduces fundamental aspects of the electrocatalytic CO 2 RR process together with a systematic examination of recent developments in Cu-based electrocatalysts for the electroreduction of CO 2 to various high-value multicarbon products. Current challenges and future trends in the development of advanced Cu-based CO 2 RR electrocatalysts providing high activity and selectivity are also discussed.

Electrocatalytic nitrite reduction not only holds significant potential in the control of nitrite contamination in the natural environment, but also is an attractive approach for sustainable ammonia synthesis. In this communication, we report that a TiO 2- x nanobelt array with oxygen vacancies on a titanium plate is able to convert nitrite into ammonia with a high faradaic efficiency of 92.7% and a large yield of 7898 μg h -1 cm -2 in alkaline solution. This monolithic catalyst also shows high durability with the maintenance of its catalytic activity for 12 h. Theoretical calculations further reveal the critical role of oxygen vacancies in nitrite electroreduction.

Electrocatalytic reduction of nitrite (NO 2 - ) to ammonia (NH 3 ) can simultaneously achieve wastewater treatment and ammonia production, but it needs efficient catalysts. Herein, Cu 2 O particles self-supported on Cu foam with enriched oxygen vacancies are developed to enable selective NO 2 - reduction to NH 3 , exhibiting a maximum NH 3 yield rate of 7510.73 μg h -1 cm -2 and high faradaic efficiency of 94.21% at -0.6 V in 0.1 M PBS containing 0.1 M NaNO 2 . Density functional theory calculations reveal the vital role of oxygen vacancies during the nitrite reduction process, as well as the reaction mechanisms and the potential limiting step involved. This work provides a new avenue to the rational design of Cu-based catalysts for NH 3 electrosynthesis.

Electrocatalytic NO reduction controls NO emission and produces NH 3 under ambient conditions. Herein, a NiO nanosheet array on titanium mesh is proposed as a highly active and selective electrocatalyst for NO reduction, attaining a faradaic efficiency of up to 90% with a NH 3 yield of 2130 μg h -1 cm -2 . Its aqueous Zn-NO battery can generate electricity with a power density of 0.88 mW cm -2 and simultaneously offer an NH 3 yield of 228 μg h -1 cm -2 . The NO electroreduction mechanism on NiO is revealed using theoretical calculations.

Electrocatalytic eight-electron nitrate (NO 3 - ) reduction is a sustainable strategy to degrade NO 3 - and convert it into high value-added ammonia (NH 3 ) but needs efficient catalysts with high activity and selectivity. Our study shows the use of Ti plate supported cobalt-phosphorus alloy film (Co-P/TP) as a highly active and selective electrocatalyst for ambient NO 3 - -to-NH 3 conversion. In 0.2 M Na 2 SO 4 with 200 ppm NO 3 - , Co-P/TP offers an NH 3 yield rate of 416.0 ± 7.2 μg h -1 cm -2 and a high faradaic efficiency of 93.6 ± 3.3% at -0.6 V and -0.3 V vs. reversible hydrogen electrode, respectively, with good durability. Noticeably, a conversion rate of 86.9% is achieved after 10 h bulk electrolysis.

Sn-doped TiO 2 nanomaterials with different amounts of Sn (1, 2.5, 5, 10, and 15 at%) were prepared by a sol-gel method and characterized by XRD, TG, DTA, EDS, XPS, DRS, SEM, BET, and PL. The photocatalytic activity of the prepared samples was investigated by measuring the degradation of rhodamine B in aqueous solution under UV light. The experimental results indicate that doping with Sn promotes phase transformation from anatase to rutile. The photocatalytic activity of TiO 2 is influenced by both the heat treatment temperature and the Sn doping concentration. 1% Sn-TiO 2 exhibits the highest degradation rate at 350 °C and 5% Sn-TiO 2 exhibits the best photocatalytic activity at 500 °C and 650 °C. The enhancement of the photocatalytic activity can be ascribed to a larger surface area and a better hydration ability, as well as less recombination of the photogenerated pairs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)