First-Principles Study of χ3-Borophene as a Candidate for Gas Sensing and the Removal of Harmful Gases.

The potential application of borophene as a sensing material for gas-sensing devices is investigated in this work. We utilize density functional theory (DFT) to systematically study the adsorption mechanism and sensing performance of χ3-borophene to search for high-sensitivity sensors for minor pollutant gases. We compare the results to those for two Pmmn borophenes. The first-principles calculations are used to analyze the sensing performance of the three different borophenes (2 Pmmn borophene, 8 Pmmn borophene, and χ3-borophene) on five leading harmful gases (CO, NH3, SO2, H2S, and NO2). The adsorption configuration, adsorption energy, and electronic properties of χ3-borophene are investigated. Our results indicate that the mechanism of adsorption on χ3-borophene is chemisorption for NO2 and physisorption for SO2 and H2S. The mode of adsorption of CO and NH3 on χ3-borophene can be both physisorption and chemisorption, depending on the initially selected sites. Analyses of the charge transfer and density of states show that χ3-borophene is selective toward the adsorption of harmful gases and that N and O atoms form covalent bonds when chemisorbed on the surface of χ3-borophene. An interesting phenomenon is that when 8 Pmmn borophene adsorbs SO2, the gas molecules are dismembered and strongly adsorb on the surface of 8 Pmmn borophene, which provides a way of generating O2 while adsorbing harmful substances. Overall, the results of this work demonstrate the potential applications of borophene as a sensing material for harmful gas sensing or removal.

The nickel phosphate rods derived from Ni-MOF with enhanced electrochemical activity for non-enzymatic glucose sensing.

In this work, spherical Ni-based metal-organic frameworks (Ni-MOFs) were used as precursors for preparing nanorod-like nickel phosphate (r-NiPO) with enhanced electro-catalytic properties in detection of glucose. It was found that the addition of nickel ion has a profound effect on construction of nickel phosphate with flower-like, rod-like, and ribbon-like structure in presence of H2PO2-. The r-NiPO consisted of multiple phases of nickel phosphate showed porous, interconnected structure and abundant active Ni(II)/Ni(III) pairs, which was beneficial to facilitate glucose oxidation. In comparison with Ni-MOF, r-NiPO exhibited the superior electrocatalytic property on oxidation of glucose because of the exposing more active Ni sites in r-NiPO than that of Ni-MOF precursor. r-NiPO modified glassy carbon electrode (r-NiPO/GCE) showed a good linear response to glucose from 1.0 µM to 3.0 mM with a high sensitivity of 3169 µA mM-1 cm-2. In addition, r-NiPO/GCE can be used to detect glucose in human serum with satisfactory recoveries (90-97%).