Nano Materials Science最新文献

Improving catalytic activity and durabilty through the structural and compositional development of bifunctional electrocatalysts with low cost, high activity and stability is a challenging issue in electrochemical water splitting. Herein, we report the fabrication of heterostructured P-CoMoO₄@NiCoP on a Ni foam substrate through interface engineering, by adjusting its composition and architecture. Benefitting from the tailored electronic structure and exposed active sites, the heterostructured P-CoMoO₄@NiCoP/NF arrays can be coordinated to boost the overall water splitting. In addition, the superhydrophilic and superaerophobic properties of P-CoMoO₄@NiCoP/NF make it conducive to water dissociation and bubble separation in the electrocatalytic process. The heterostructured P-CoMoO₄@NiCoP/NF exhibits excellent bifunctional electrocatalysis activity with a low overpotential of 66 ​mV at 10 ​mA ​cm⁻² for HER and 252 ​mV at 100 ​mA ​cm⁻² for OER. Only 1.62 ​V potential is required to deliver 20 ​mA ​cm⁻² in a two-electrode electrolysis system, providing a decent overall water splitting performance. The rational construction of the heterostructure makes it possible to regulate the electronic structures and active sites of the electrocatalysts to promote their catalytic activity.

Bimetallic Pt-skin catalyst is a class of near-surface alloy (NSA) that owns a high degree of control over composition. Herein, density functional theory (DFT) is used to calculate the energetics of oxygen reduction reaction (ORR) on Pt-skin over Ir, Pd and Au substrates. A Brønsted-Evans-Polanyi (BEP) relationship can be determined for the oxygen molecule dissociation. The binding energy of both atomic oxygen and hydroxyl radical is found to correlate well with the d band center of Pt-skin atoms. Their catalytic activities show the volcano relationship as the positions of each substrate in the periodic table. The effect of surface strain, band structure and charge transfer on the d band center is well studied, and it can be found that the surface strain effect plays a dominant role for all Pt-skin catalysts. Ir substrate makes the d band center of Pt-skin go far away from the Fermi level, while Au substrate makes it move towards the Fermi level. Being different from both Ir and Au, Pd substrate makes the d band center of Pt-skin comparable with the monometallic Pt.

Two novel two-dimensional (2D) supramolecular organic frameworks were fabricated in water based on the encapsulation-enhanced donor-acceptor interaction between the methyl viologen (MV) units, methoxy naphthyl (MN) units, and CB [8]. The tetraphenylethylene (TPE) derivatives 1 with four MV units were employed as rigid building blocks and the two MN units modified oligoethylene glycol derivatives 2 and 3 served as flexible edges, respectively. The obtained two SOFs have obvious sheet-like structures and exhibit fluorescence emission at 350–500 ​nm. In addition, these two SOFs were employed for the luminescent detection of Cr(VI) and Mn(VII) in aqueous solutions, and the detection limits of CrO₄²⁻, Cr₂O₇²⁻, and MnO₄⁻ were calculated in a very low concentration range, indicating that these two SOFs can serve as a potential sensor for Cr(VI) and Mn(VII) detection in water. This work constructs two SOFs in an aqueous solution through a facile method and further enriches the applications of SOFs.

Lignin is the most abundant aromatic polymer in nature, which is rich in a large number of benzene ring structures and active functional groups. The molecular structure of lignin has unique designability and controllability, and is a class of functional materials with great application prospects in energy storage and conversion. Here, this review firstly focuses on the concept, classification, and physicochemical property of lignin. Then, the application research of lignin in the field of electrochemical storage materials and devices are summarized, such as lignin-carbon materials and lignin-carbon composites in supercapacitors and secondary batteries. Finally, this review points out the bottlenecks that need to be solved urgently and the prospects for future research priorities.

Photocatalytic reduction of CO₂ is considered as a kind of promising technologies for solving the greenhouse effect. Herein, a novel hybrid structure of g-C₃N₄/ZnO/Ti₃C₂ photocatalysts was designed and fabricated to investigate their abilities for CO₂ reduction. As demonstration, heterojunction of g-C₃N₄/ZnO can improve photogenerated carriers’ separation, the addition of Ti₃C₂ fragments can further facilitate the photocatalytic performance from CO₂ to CO. Hence, g-C₃N₄/ZnO/Ti₃C₂ has efficiently increased CO production by 8 and 12 times than pristine g-C₃N₄ and ZnO, respectively. Which is ascribed to the photogenerated charge migration promoted by metallic Ti₃C₂. This work provides a guideline for designing efficient hybrid catalysts on other applications in the renewable energy fields.

The d-band state of materials is an important descriptor for activity of oxygen evolution reaction (OER). For NiO materials, there is rarely concern about tuning their d-band states to tailor the OER behaviors. Herein, NiO nanocrystals with doping small amount of La³⁺ were used to regulate d-band states for promoting OER activity. Density of states calculations based on density functional theory revealed that La³⁺ doping produced upper shift of d-band center, which would induce stronger electronic interaction between surface Ni atoms and species of oxygen evolution reaction intermediates. Further density functional theory calculation illustrated that La³⁺ doped NiO possessed reduced Gibbs free energy in adsorbing species of OER intermediate. Predicted by theoretical calculations, trace La³⁺ was introduced into crystal lattice of NiO nanoparticles. The La³⁺ doped NiO nanocrystal showed much promoted OER activity than corresponding pristine NiO product. Further electrochemical analysis revealed that La³⁺ doping into NiO increased the intrinsic activity such as improved active sites and reduced charge transfer resistance. The in-situ Raman spectra suggested that NiO phase in La³⁺ doped NiO could be better maintained than pristine NiO during the OER. This work provides an effective strategy to tune the d-band center of NiO for efficient electrocatalytic OER.

Integrated electrocatalysts (IECs) containing well-defined functional materials directly grown on the current collector have sparked increasing interest in the fields of electrocatalysis owing to efficient activity, high stability and the fact that they are easily assembled into devices. Recently, metal organic frameworks (MOFs) provide a promising platform for constructing advanced IECs because of their properties of low cost, large surface area and efficient structural tunability. In this review, the design principles of state-of-the-art IECs based on MOFs are presented, including by hydrothermal/solvothermal, template-directed, electrospinning, electrodeposition and other methods. The high performance of MOF-derived IECs has also been demonstrated in electrocatalytic gas-involved reactions. This is promising for green energy storage and conversion. The structure-activity relationship and performance improvement mechanism of IECs are uncovered by discussing some in situ technologies for IECs. Finally, we provide an outlook on the challenges and prospects in this booming field.

The vigorous development of two-dimensional (2D) materials brings about numerous opportunities for lithium-ion batteries (LIBs) due to their unique 2D layered structure, large specific surface area, outstanding mechanical and flexibility properties, etc. Modern technologies for production of 2D materials include but are not limited to mechanochemical (solid-state/liquid-phase) exfoliation, the solvothermal method and chemical vapor deposition. In this review, strategies leading to the production of 2D materials via solid-state mechanochemistry featuring traditional high energy ball-milling and Sichuan University patented pan-milling are highlighted. The mechanism involving exfoliation, edge selective carbon radical generation of the 2D materials is delineated and this is followed by detailed discussion on representative mechanochemical techniques for tailored and improved lithium-ion storage performance. In the light of the advantages of the solid-state mechanochemical method, there is great promise for the commercialization of 2D materials for the next-generation high performance LIBs.

Pure Zn coatings easily lose their protective performance after biofouling because they have no antibacterial effect under visible light. In this study, we fabricate a new antibacterial Zn composite coating using electrodeposition to couple Fe³⁺-doped alkalized g-C₃N₄ (AKCN-Fe) into an existing Zn coating and show that the AKCN-Fe enhances antibacterial property of the Zn coating under visible light. We attribute this enhancement to the high photocatalytic performance, high loading content, and good dispersion of AKCN-Fe. In addition, the photocatalytic antibacterial mechanism of the composite coating is supported by scavenger experiments and electron paramagnetic resonance (EPR) measurements, suggesting that superoxide ($·{\text{O}}_2^{-}$) and hydroxyl radical (·OH) play main and secondary roles, respectively.