Highly efficient nanoporous CoBP electrocatalyst for hydrogen evolution reaction

Water splitting is an environment friendly and efficient way to produce hydrogen.Highly efficient and low-cost non-noble metal catalysts play an important role in hydrogen evolution reaction(HER).Dealloying is a simple method to prepare three-dimensional self-supporting nanoporous materials without conductive supports and binders.In this work,we prepared self-supporting nanoporous CoBP electrocatalyst by dealloying method.The influence of the synergistic effect of nonmetallic elements on catalytic activity was investigated.The synergistic electronic effect of Co,B and P atoms on the surface optimizes the H atoms desorption and results in superior HER activity.The bi-continuous structure of nanoporous CoBP provides more active area and favors of electron and electrolyte transfer.The nanoporous CoBP with the B/P atomic ratio of 1/3 exhibits low overpotential of 42 mV at 10 mA·cm^(-2),small Tafel slope of 39.8 mV·dec-1 and good long-term stability with no performance decrease for 20 h in alkaline solution.

Electrodeposition of self-supported NiMo amorphous coating as an efficient and stable catalyst for hydrogen evolution reaction

NiMo-based materials have been identified as potential candidates of Pt/C electrocatalysts for hydrogen evolution reaction(HER)due to appropriate binding energy to hydrogen,and good resistance to corrosive environments.However,little work has been carried out to enhance the catalytic performance in large-scale water-alkali electrolysis.The NoMo amorphous coating,as a highefficient and cost-effective catalyst toward HER,was synthesized by a facile electrodeposition strategy in this study.The effects of the pH value of electrolyte on the structure and HER activity of NiMo coating were investigated.The as-prepared NiMo_((pH10))exhibited the highest HER activity with overpotentials of 63.9 and 157.1 mV(vs.RHE,with 80%potential drop due to electrical resistance(iR)compensation)at the current density of-10 mA·cm^(-2)and-100 mA·cm^(-2).This NiMo_((pH10))coating also had excellent long-term durability of up to100 h stable operation under the constant current density of-100 mA·cm^(-2).The rapid HER kinetics and outstanding endurance can be ascribed to the NiMo compact coating with amorphous structures as well as good contact between NiMo coating and Ni foam substrate,endowing it grand feasibility in practical industrial applications.

Flower-like CuS/graphene oxide with photothermal and enhanced photocatalytic effect for rapid bacteria-killing using visible light

Pathogenic bacteria have been threatening the daily life of human beings.More effective methods without causing drug-resistance of bacteria need to be developed to fight against these pathogens.Herein,flower-like CuS/-graphene oxide(GO)hybrids have been successfully synthesized via simple one-pot hydrothermal process.GO worked as an excellent electron acceptor to transport the photogenerated electrons from CuS,which can suppress the recombination of hole–electron pairs efficiently,thus enhancing the photocatalytic property.In addition,the morphology of CuS and GO with high specific surface area and the increased defect in GO also improved photocatalytic performance of the hybrid.Owing to the synergy of photothermal,enhanced photocatalytic effect and released Cu ions,CuS/GO exhibited outstanding antibacterial efficacy under visible light irradiation for 15 min.Additionally,the hybrid showed great biocompatibility to L929 cell.Hence,the synthesized CuS/GO would be a promising antibacterial material for daily life including rapid water disinfection and wounds sterilization.

Preparation of hydroxyapatite layer on Ti-based bulk metallic glasses by acid and alkali pre-treatment

In this paper, a thin calcium phosphate layer was prepared on the surface of Ti4oZr10Cu36Pd14 bulk metallic glasses （BMGs）. All samples were dipped in HNO3 aqueous solution and boiled in 1.2 mol-L-I NaOH aqueous solution. After the two preliminary treatment steps, they were soaked in simulated body fluid （SBF） to form an apatite layer on the surface. After immersion for 12 days, a coating composed mainly of Ca-P particles was rapidly deposited on the surface of Ti40Zr10Cu36Pd14 bulk metallic glasses. The surfaces of chemically treated sam- ples and the samples after immersion in SBF were char- acterized by X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS）, field emission scanning electron microscopy （FESEM）, and energy dispersive spectroscopy （EDS）. Analysis results indicate that this apatite coating consists of Ca-P particles with different diameters. In addition, the Ca/P ratio of the apatite coatings immersed for 14 days is 1.62, which is close to that of hydroxyapatite （HA）.

ALD-induced TiO_(2)/Ag nanofilm for rapid surface photodynamic ion sterilization

The daily life of people in the intelligent age is inseparable from electronic device,and a number of bacteria on touch screens are increasingly threatening the health of users.Herein,a photocatalytic TiO_(2)/Ag thin film was synthesized on a glass by atomic layer deposition and subsequent in situ reduction.Ultraviolet-visible(UV-Vis)spectra showed that this film can harvest the simulated solar light more efficiently than that of pristine TiO_(2).The antibacterial tests in vitro showed that the antibacterial efficiency of the TiO_(2)/Ag film against S.aureus and E.coli was 98.2%and 98.6%,under visible light irradiation for 5 min.The underlying mechanism was that the in-situ reduction of Ag on the surface of TiO_(2)reduced the bandgap of TiO_(2)from 3.44 to 2.61 eV due to the formation of Schottky heterojunction at the interface between TiO_(2)and Ag.Thus,TiO_(2)/Ag can generate more reactive oxygen species for bacterial inactivation on the surface of electronic screens.More importantly,the TiO_(2)/Ag film had great biocompatibility with/without light irradiation.The platform not only provides a more convenient choice for the traditional antibacterial mode but also has limitless possibilities for application in the field of billions of touch screens.

Zr_(55)Al_(10)Ni_(5)Cu_(30)amorphous alloy film prepared by magnetron sputtering method

In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).

Photothermal-controlled sustainable degradation of protective coating modified Mg alloy using near-infrared light

Controlling the corrosion rate is critical for practical applications of Mg-based alloys. In this work, we constructed a protective coating of hybrid polycaprolactone(H-PCL)/indocyanine green(ICG) on AZ31 Mg alloy,whose degradation rate was controlled by 808-nm nearinfrared(NIR) light irradiation. The corrosion behaviors of H-PCL/ICG coated Mg alloys were systematically investigated by potentiodynamic polarization tests, electrochemical impedance spectroscopy(EIS) and hydrogen evolution experiments. The results disclosed that the H-PCL/ICG composite coating could effectively protect Mg alloy from corroding without NIR light irradiation. In contrast, under 808-nm NIR light irradiation, the corrosion resistance of this composite coating was decreased significantly, i.e., the corrosion current density(i_(corr))increasedfrom(8.81 ± 1.068) 9 10^(-8) to(1.22 ± 0.545) 9 10^(-6) A·cm^(-2). This is because the component of ICG in the coating was excited to produce heat locally, which triggered the glass transition temperature(T_(g)) of H-PCL in the coating, resulting in the motion of the molecular chain segment. Consequently, the electrolytes penetrated the coating and corroded the Mg substrate. In vitro biological experiment indicated that the synthesized coating exhibited good cytocompatibility.Hence, these findings will provide a new strategy for designing novel photoresponsive coatings to remotely adjust the degradation rate of biodegradable metals for biomedical applications.