Electrochemical deposited amorphous FeNi hydroxide electrode for oxygen evolution reaction

The electrodeposition approach is significant in electrode fabrication for practical application.Herein,the electrodeposited amorphous NiFe hydroxide species for oxygen evolution reaction (OER) in water splitting reaction is demonstrated by revealing the synergistic effect influenced by the support electrode of Fe and Ni foil and the contents of Fe and Ni in the electrolyte.All the electrodeposited samples have an amorphous structure and similar profiles of binding energy and chemical states for Fe and Ni as characterized by the spectroscopic techniques.While the support effect and Fe/Ni synergistic effect are indeed observed for the varied catalytic performances observed for the different electrodes;the Ni foil supported catalyst exhibits much higher performance than that of the Fe foil supported catalyst,and the different redox potentials of Ni species in the different Fe/Ni electrode resulting from the Fe–Ni synergism are observed in the cyclic voltammetry curve analysis.The surface roughness and the electrochemical surface area are also influenced by the support effect and the Fe/Ni ratio in the plating electrolyte.The optimal electrode shows a very low overpotential of~200 mV to reach 10 mA cm^(-2),and very high catalytic stability by the consecutive cyclic voltammetry measurements and 20 h stability test.Though it has the largest electrochemical surface area,the highest catalytic efficiency for these active sites is also indicated by the specific activity and turnover frequency polarization curves.The current work shows the effective experience for the electrodeposited Fe/Ni based catalysts in large-scale fabrication,which can be more practical for hydrogen generation in the alkaline water electrolysis.

Enhanced photocatalytic performance of Bi_(2)O_(2)CO_(3)/Bi_(4)O_(5)Br_(2)/reduced graphene oxide Z-schemehe terojunction via a one-pot room-temperature synthesis

Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies(OVs)effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC,showing improved reduction/oxidation ability.Particularly,rGO is an acceptor of the electrons from the conduction band of BOC.Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation.With layered nanosheet structure,rich OVs,high specific surface area,and increased utilization efficiency of visible light,the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes,thereby generating more·O_(2)^(-)and h^(+).The photocatalytic reduction efficiency of CO_(2)to CO(12.91μmol/(g·hr))is three times higher than that of BOC(4.18μmol/(g·hr)).Moreover,it also achieved almost 100%removal of Rhodamine B and cyanobacterial cells within 2 hours.

Bird nest-like zinc oxide nanostructures for sensitive electrochemical glucose biosensor

In this research,a novel bird nest-like zinc oxide(BN-ZnO)nanostructures were prepared by a simple solvothermal method.A sensitive electrochemical glucose biosensor was for the first time developed based on the immobilization of glucose oxidase(GOx)on nanostructured BN-ZnO modified electrode.The BN-ZnO nanostructure and the resultant biosensor were characterized by scanning electron microscope,X-ray diffraction spectroscopy,Fourier transform infrared spectroscopy,and electrochemical impedance spectroscopy.BN-ZnO nanostructures have large specific surface area and can load large amounts of GOx molecules.Meanwhile,BN-ZnO provides an excellent microenvironment to retain the native bioactivity of enzymes and to promote direct electron transfer between GOx and electrode surface.The proposed biosensor shows a wide linear range of 0.005–1.6 mmol/L,high sensitivity of15.6 mA L mol^(-1)cm^(-2)with a low detection limit of 0.004 mmol/L.The resulting biosensor also shows excellent selectivity,acceptable stability and reproducibility,and can be successfully applied in the detection of glucose in human serum samples at-0.37 V.

Oxygen vacancies induced narrow band gap of BiOCl for efficient visible-light catalytic performance from double radicals

In this work,a high-efficiency photocatalytic BiOCl material with a visible light absorption range was successfully prepared by one-pot molecular self-assembly and particle recrystallization method at room temperature.In the process of crystal growth,tartaric acid,as a structure control agent,gradually transforms the stacked two-dimensional nano-sheet-like BiOCl into a hierarchical structure composed of petallike nano-sheets through hydrogen bonding.Besides,the acid etching of organic carboxylic acid on the crystal surface increases the number of micropores and mesopores,thereby the reaction interface.The thiourea(TU)molecules adsorbed on the BiOCl surface with a strong electronic effect introduce oxygen vacancies(OVs)under the condition of low oxygen content.The synergistic effect of hierarchical structure and OVs reduces the recombination of photogenerated carriers,but absorbs more O_(2)and OH−to generate a large number of superoxide radicals(·O_(2)−)and hydroxyl radicals(·OH)effectively.The photocatalytic performance of the synthesized BiOCl material has been significantly improved,and it can effectively degrade 94.15%of rhodamine B(RhB)within 20 min.Furthermore,90.95%of tetracycline(TC),93.76%of ciprofloxacin(CIP),and 85.53%of methyl orange(MO)can be removed in 80 min.Therefore,our work provides an effective method for preparing BiOCl with visible light catalytic activity,which,of course,can be used to treat and repair actual environmental problems under mild conditions.

Tofukasu-derived biochar with interconnected and hierarchical pores for high efficient removal of Cr (Ⅵ)

Herein,we report the synthesis of interconnected hierarchical pore biochar(HTB)via an ice-templating strategy using bio-waste(tofukasu).The abundance of N-and O-containing functional groups in tofukasu makes it easy to form hydrogen bonds with water molecules and water clusters,resulting in nano-micro structures like ice clusters and snow crystals during freezing process.More importantly,tofukasu will be squeezed by micron-scale snow crystals to form coiled sheet-like structures,and its surface and interior will be affected by needle-like ice nanocrystals from several nanometers to tens of nanometers to form transverse groove needles and mesopores.The ice crystals are then removed by sublimation with tofukasu,leaving the interconnected pore structure intact.Therefore,the ice template synthesis strategy endowed the interconnected hierarchical pore structure of HTB with a large specific surface area(SBET,733 m^(2)⋅g^(−1))and hierarchical porosity(30.30%for mesopores/total pore volume ratio),which is significantly higher than the normal dry treated tofukasu biochar(TB),which had a SBET of 436 m^(2)⋅g^(−1) and contained 1.53%mesopores.In addition,the sheet-like structure with interconnected pores of HTB favors high exposure of active sites(N-and O-containing functional groups),and a fast electron transport rate.As a result,HTB had an excellent adsorption capacity of 159.65 mg⋅g^(−1),which is 4.7 times that of typical block biochar of TB(33.89 mg⋅g^(−1))according to Langmuir model.Electrochemical characterization,FTIR and XPS analysis showed that the mechanism of Cr(Ⅵ)removal by HTB included electrostatic attraction,pore filling,reduction and surface complexation.