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The use of vanadium(V)-based materials as electrode materials in electrochemical energy storage (EES) devices is promising due to their structural and chemical variety, abundance, and low cost. V-based materials with a layered structure and high multielectron transfer in the redox reaction have been actively explored for energy storage. Our current work presents the structural and electrochemical properties of a vanadium-based composite with TiO2@Ti3C2MXene, referred to as VM. This composite is obtained through the in situ thermal decomposition of the VO2(OH)/Ti3C2mixture, which is achieved by solution mixing and drying. The material structure is confirmed using various characterization tools, which establish an orthorhombic V2O5nanostructure compositing with nanocrystalline TiO2@Ti3C2. VM with 5 wt % MXene, referred to as VM5, can achieve 460 mAhg–1at a current density of 0.1 Ag1–and 290 mAhg–1at 1 Ag1–, with an average coulombic efficiency of 98.5%. The presence of the V2O5/TiO2(nanocrystals) heterojunction attached with Ti3C2sheets contributed to reduced charge transfer resistance. The cyclic stability shows a capacity retention of 62% over 500 cycles at 1 Ag1–(4C rate, where 1C equals 0.25 Ag1–) with a 0.22 capacity drop with each cycle. Dunn’s approach to examining the charge storage mechanism demonstrates 72% contribution of the surface-dominant capacitive process and 28% of the diffusion-controlled intercalation process at 0.4 mVs–1, suggesting a potential high-performance pseudocapacitive hybrid electrode material for lithium-ion batteries.

The reconsideration of aqueous zinc-ion batteries (ZIBs) has been motivated by the attractive zinc metal, which stands out for its high theoretical capacity and cost efficiency. Nonetheless, detrimental side reactions triggered by the remarkable reactivity of H2O molecules and rampant dendrite growth significantly compromise the stability of the zinc metal anode. Herein, a novel approach was proposed by leveraging the unique properties of acrylamide (AM) molecules to increase the driving force for nucleation and parasitic reactions. Combined with experimental data and theoretical simulations, it is demonstrated that the incorporation of AM additive can reconstruct the solvation shell around Zn2+and reduce the number of active H2O molecules, thereby effectively reducing the H2O molecule decomposition. Consequently, the Zn//Zn symmetric batteries with AM-containing ZnSO4electrolytes can attain excellent long-term performances over 2000 h at 1 mA cm–2and nearly 500 h at 10 mA cm–2. The Zn//VO2full batteries still display improved cycling performances and a high initial discharging capacity of 227 mA h g–1at 3 A g–1compared to the ZnSO4electrolyte. This electrolyte optimization strategy offers new insights for achieving long-term ZIBs and advances the progress of ZIBs in energy storage.

This study focuses on a fabrication technique that enhances diamond particle incorporation in nickel-phosphorus/diamond (Ni–P/diamond) composite coatings. Direct current co-electrodeposition with pulse-stirring was employed. Scanning electron microscopy (SEM) revealed nodular structures in the Ni–P/diamond composite coating. Cross-sectional analysis and energy dispersive X-ray spectroscopy (EDS) were used to quantitatively compare the amount of diamond particles, P content and Ni content in the composite coatings fabricated using different stirring cycles and current densities. Pulse-stirring was found to yield a multilayer structure and a higher amount of deposited diamond particles. Repeated off- and on-stirring patterns allowed the diamond particles to deposit through gravitation-assisted electrodeposition, while the short cycles of system agitation allowed diamond particles sedimented outside the coating area to become redispersed with a greater likelihood of incorporation into the coatings. The Vickers hardness test was performed to measure the hardness of the obtained composite coatings. The pulse-stirring sample fabricated using a 0.03 A/cm2current density was shown to have a maximal hardness value of 912 ± 10.94 HV0.1. This accounted for a 17.82 % increase in hardness compared to that of a sample prepared using continuous stirring. Higher diamond content in the sample fabricated by the pulse-stirring technique also exhibited highest wear resistance and lowest friction coefficient.

Developing a low-cost photocatalyst with efficient performance is significant for practical application of solar-to-fuel conversion. Here, we first adopt a facile method to synthesize Bi2O2CO3-modified g-C3N4heterojunction via in situ thermal growth. Bi2O2CO3nanoparticles on g-C3N4nanosheets play a vital role in improving the photocatalytic activity of splitting water for hydrogen production. The activity of Bi2O2CO3/g-C3N4heterojunction during 5 h reaches 965 μmol·g–1·h–1, which is much higher than that of pure g-C3N4(337 μmol·g–1·h–1) or other modified g-C3N4materials. The significantly enhanced photocatalytic activity is attributed to direct Z-scheme system construction, resulting in a superior charge carrier separation ability. Theoretical calculations further reveal the redistribution of charge carrier at interface between Bi2O2CO3and g-C3N4. This work provides new direction to synthesize g-C3N4-based heterojunction with high photocatalytic performance for alleviating energy and environmental issues.

Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity. However, sluggish Na+diffusion and low electronic conductivity of selenides still hinder their practical applications. Herein, FeSe2-xSxmicrospheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2as both the Fe and S source, followed by gas phase selenization. The density functional theory calculation results reveal that S doping not only improves the Na adsorption, but also lower the diffusion energy barrier of Na atoms at the S doping sites, at the same time enhance the electronic conductivity of FeSe2-xSx. The carbon-free nature of the FeSe2-xSxmicrospheres results in a low specific surface area and a high tap density, leading to an initial columbic efficiency of 85.6%. Compared with pure FeSe2, such FeSe2-xSxdelivers a high reversible capacity of 373.6 mAh·g−1at a high current density of 5 ​A·g−1after 2000 cycles and an enhanced rate performance of 305.8 mAh·g−1at even 50 ​A·g−1. Finally, the FeSe2-xSx//NVP pouch cells have been assembled, achieving high energy and volumetric energy densities of 118 ​Wh·kg−1and 272 ​mWh·cm−3, respectively, confirming the potential of applications for the FeSe2-xSxmicrospheres.

The rechargeable Li-O2battery endowed with high theoretical specific energy density has sparked intense research interest as a promising energy storage system. However, the intrinsic high activity of Li anode, especially to moisture, usually leads to inferior electrochemical performance of Li-O2battery in humid environments, hindering its widespread application. To settle the trouble of poor moisture tolerance, fabricating a water-proof layer on the Li-metal anode could be an effective tactic. Herein, a facile strategy for constructing an ibuprofen-based protective layer on the Li anode has been proposed to realize highly rechargeable Li-O2battery in humid atmosphere. Due to the in-situreaction between ibuprofen reagent and metallic Li, the protective layer with a thickness of ∼30 µm has been uniformly deposited on the surface of Li anode. Particularly, the protective layer, consisting of a large amount of hydrophobic alkyl group and benzene ring, can significantly resist water ingress and enhance the electrochemical stability of Li anode. As a result, the Li-O2battery based on the protected Li anode achieves a long cycle life of 210 h (21 cycles at 1000 mAh/g, 200 mA/g) in highly moist atmosphere with relative humidity (RH) of 68%. This convenient and efficient strategy offers novel design concept of water-resistant metal anode, and paves the way to the promising future prospect for the high-energy Li-O2battery implementing in the ambient atmosphere.

Titanium carbide @ carbon-doped titanium dioxide (TiC@C-TiO2) core-shell nanostructures are designed, prepared and demonstrated for the application in lithium ion battery anode. Synthesis of these specific core-shell nanostructures is achieved via a facile, novel, and one-pot approach using oxidative growth of C-TiO2onto TiC nanoparticles, which has a higher electrochemical activity than those of pure P25 and TiC nanoparticles. The core-shell nanostructured anodes exhibit a high lithium storage capacity (352.8 mAh g−1at 100 mA g−1), good rate capability (253.6 mAh g−1at 1 A g−1, 158.1 mAh g−1at 10 A g−1), and outstanding cycle stability in lithium ion batteries (LIBs) (~ 150 mAh g−1at 10 A g−1after 400 cycles), which is about 48 times and 7 times higher than that of TiO2electrode (~ 3.3 mAh g−1at 10 A g−1) and TiC (~ 25 mAh g−1at 10 A g−1). According to the first-principle calculation, the ultrahigh capacity and cycle stability of the as-prepared anode is ascribed to the enhancement of Li+absorption and diffusion ability through formation of C-TiO2porous layer onto the conductive TiC particles. Moreover, the increase of electron density around the Fermi level is found to be mainly caused by the core-shell nanostructures. The results demonstrate that the presence of TiC plays an important role in providing high conductivity and the novel core-shell nanostructure can buffer the huge volume expansion and contraction during prolonged cycling, resulting in great potential applications in LIBs.

Graphitic carbon nitride (g-C3N4) photocatalysts have attracted much attention towards harvesting solar energy for applications in energy and environment sectors. However, separation of electron-hole pairs is an intrinsic problem for the bulk g-C3N4. Here, we report the tiny amount of carbon doped TiO2modified g-C3N4(C-TiO2/g-C3N4) with a narrow bandgap and prolonged lifetime of charge carriers. This heterojunction photocatalysts were successfully fabricated via a facile heat treatment under atmosphere. The enhanced separation of photogenerated charge carriers and narrow band gap confer superior photocatalytic activities with 5.728mmol/g photogenerated hydrogen gas for 5h and 52.395mmol/g for 64h in triethanolamine aqueous solution. The apparent quantum efficiency of C-TiO2/g-C3N4is ~ 6.2% under 420nm irradiation, which is about 2.4 times higher than the corresponding value 2.6% of pristine g-C3N4. This photocatalyst with excellent photocatalytic performance and photo-stability can work as a promising candidate to applicate in solar-to-fuel conversion and environmental remediation.