Adsorption of HCN on Ni/Pt(111)Bimetallic Surfaces Investigated with Density Functional Theory Method

We applied periodic density-functional theory to investigate the adsorption of HCN on x Ni@Pt（111） bimetallic surfaces（x = 1~4）. The results have been compared with those obtained on pure Ni（111） and Pt（111） surfaces. For all bimetallic surfaces,HCN is preferentially tilted with the CN bond parallel to the surface,and adsorption energies increase with an increasing number of layer Ni atoms on the surface. The adsorption energies of HCN on all bimetallic surfaces are larger than that on the Pt（111） surface,whereas the adsorption energies of HCN on 3Ni@Pt（111） and 4Ni@Pt（111） are larger than that on the Ni（111） surface,indicating that the introduction of Ni to the Pt catalyst could increase the activity of bimetallic catalyst in the hydrogenation reaction for nitriles. Larger adsorption energy of HCN leads to a longer C–N bond length and a smaller CN vibrational frequency. The analysis of Bader charge and vibrational frequencies showed obvious weakening of the adsorbed C–N bond and an indication of sp2 hybridization of both carbon and nitrogen atoms.

Ce(Ⅲ)-modulation over non-enzymatic Pt/CeO_(2)/GO biosensor with outstanding sensitivity and stability for lactic acid detection

A series of non-enzymatic graphene functionalized biosensors was developed via deposition precipitation method for lactic acid(LA) detection,which we re characterized by transmission electron micro scopy(TEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),gas chromatography-mass spectrometry,liquid chromatography-mass spectro metry,and proton nuclear magnetic re sonance(~1H NMR).The electrochemical performances of the non-enzymatic biosensors were measured by means of the electrochemical impedance spectroscopy(EIS) and cyclic voltammetry(CV) method.The comprehensive analysis of structures shows that Pt,CeO_(2),and GO components interact with each other.During the storing and releasing oxygen,the valence ratio of Ce^(3+)/Ce^(4+) and the number of oxygen vacancies in CeO_(2) change accordingly,which can be conducive to increasing electronic transmission capacity and finally leads to the improvement of electrocatalytic performance.Among them,the Pt/CeO_(2)/GO biosensor containing 0.47 at% platinum exhibits an excellent electrochemical detection performance with high sensitivity of 12.3 μA·L/(mmol·cm^(2)) and a low limit of detection(LOD) of 5.12 μmol/L in a wide linear range from 10 to 900 μmol/L.In addition,the proposed biosensor possesses a promising anti-interference capability,as well as high stability and good reproducibility,which was assessed by testing the cyclic voltammogram in 0.1 mol/L lactic acid one year later.The underlying mechanism was proposed for electrochemical oxidation of LA to carbon dioxide and acetic acid with the synergistic effect among Pt,CeO_(2),and GO.Furthermore,the results of the standard addition method in real samples(human serum and urine samples) reveal that the lactic acid detection of the non-enzymatic Pt/CeO_(2)/GO biosensor is accompanied by high reliability.Thus,it will be a valuable biosensor for in vitro detection of lactic acid level in clinical samples.