MOF assisted synthesis of new porous nickel phosphate nanorods as an advanced electrode material for energy storage application

Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions

Among the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2·8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed.

Topochemically synthesized MoS2 nanosheets: A high performance electrode for wide-temperature tolerant aqueous supercapacitors

This work describes the formation of two-dimensional molybdenum di-sulfide (MoS₂) nanosheets via topochemical sulfurization of MoO₃ microplates and its applications towards wide-temperature tolerant supercapacitors. Physico-chemical characterizations such as XRD, FE-SEM, HR-TEM, XPS and elemental mapping analysis revealed the formation of MoS₂ nanosheets with lateral size in the range of 200 nm. The electrochemical properties of the MoS₂ electrode using three-electrode configuration tests revealed the presence of pseudocapacitive mechanism of charge-storage with a high capacitance (119.38 F g^-1) from cyclic voltammetry profiles and superior cyclic stability of 95.1% over 2000 cycles. The symmetric supercapacitor (SSC) fabricated using MoS₂ electrodes delivered a high-energy density (6.56 Wh kg^-1) and high-power density (2500 W kg^-1) with long cycle life. The electrochemical performance of the MoS₂ SSC exhibited ~121% improvement at 80 °C compared to that achieved at 20 °C and the mechanism of improved properties were examined with the use of electrochemical impedance spectroscopy. These experimental results indicate usefulness of topochemically synthesized MoS₂ for construction of wide-temperature tolerant supercapacitors that can be useful in a variety of industrial sectors.

Nanocomposites based on quasi-networked Au1.5Pt1Co1 ternary alloy nanoparticles and decorated with poly-L-cysteine film for the electrocatalytic application of hydroquinone sensing

A mildly one-pot method is developed for the synthesis of quasi-networked Au_1.5Pt₁Co₁ ternary alloy nanoparticles (TANPs) at room temperature through the co-reduction of AuCl₄^-, PtCl₆^- and Co²⁺ with hydrazine hydrate. Characterizations of XRD, XPS, HRTEM, EDS and SAED successfully reveal the crystal structure, composition, valence and morphology of Au_1.5Pt₁Co₁ TANPs, respectively. The glassy carbon electrode (GCE) modified by Au_1.5Pt₁Co₁ TANPs with good dispersion and multi-density surface defects occupies the optimal electrochemical active surface area (ECSA). After the coated poly-L-cysteine (P-L-Cys) film on the Au_1.5Pt₁Co₁/GCE surface, the morphology, element mapping and surface roughness of the P-L-Cys/Au_1.5Pt₁Co₁/GCE are investigated via FESEM and AFM to verify continuous electrode modification processes. The electrochemical behaviors of the composite electrode for hydroquinone (HQ) are evaluated by cyclic voltammetry (CV) with interfacial properties of adsorption and diffusion. Differential pulse voltammetry (DPV) for HQ electrochemical sensing at 0.10 V (vs. SCE) exhibits two linear response ranges from 0.1 to 30 and 30-200 μM, respectively. A low detection limit (S/N = 3) of 0.045 μM is obtained with a sensitivity of 4.247 μA μM^-1·cm^-2. The resulting P-L-Cys/Au_1.5Pt₁Co₁/GCE also presents ascendant selectivity, repeatability, reproducibility and stability. In addition, the established method is applied to the assessment of the HQ level in real water samples (mineral water, tap water and lake water) with the satisfactory results of spiked recoveries. The sensor may become a promising tool for the trace analysis of the electroactive substance in food or environmental samples.

Fabrication of a Promising Hierarchical Porous Surface on Titanium for Promoting Biocompatibility

The effects of the nano-titanium hydrides (nano-γ-TiH) phase on the formation of nanoporous Ti oxide layer by the potential approach (hydrogen fluoride (HF) pretreatment and sodium hydroxide (NaOH) anodization) were investigated using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy. The nano-γ-TiH phase was formed by the HF pretreatment with various current densities. After the NaOH anodization, the nano-γ-TiH phase was dissolved and transformed into nanoporous rutile-Ti dioxide (R-TiO2). As the Ti underwent HF pretreatment and NaOH anodization, the microstructure on the surface layer was transformed from α-Ti → (α-Ti + nano-γ-TiH) → (α-Ti + R-TiO2). In-vitro biocompatibility also indicated that the Ti with a hierarchical porous (micro and nanoporous) TiO2 surface possessed great potential to enhance cell adhesion ability. Thus, the potential approach can be utilized to fabricate a promising hierarchical porous surface on the Ti implant for promoting biocompatibility.