No abstract

No abstract

No abstract

Mercury film electrodes used in in-situ monitoring systems suffer from the drawbacks of secondary pollution and attenuation. To overcome these problems, a boron-doped diamond (BDD) film electrode was developed that was non-polluting and could be used for simultaneous detection and long durations. The concentrations of Cd 2 + and Pb 2 + in mixed solution were measured simultaneously, and the detection performances of the mercury film and BDD electrodes were systemically compared, to evaluate the feasibility of replacing mercury film electrodes with BDD electrodes. The effects of enrichment time and electrode surface state on the stripping peak currents of Cd 2 + and Pb 2 + were investigated. Optimum conditions were an enrichment time of 200 s and a hydrogen terminated electrode surface state. The optimized BDD electrode exhibited good performance characteristics: 1) The linear relationship between the ion concentration and the peak current was excellent (linear correlation coefficients (R 2 ) of the calibration curves for Cd 2 + and Pb 2 + were 0.995 and 0.998, respectively). The spiked recovery ranges of Cd 2 + and Pb 2 + in three spike experiments were 93.5% to 99.4% and 93.7% to 101.3%, respectively. 2) The detection limits for Cd 2 + and Pb 2 + were low, 3.39 μg/L and 3.62 μg/L, respectively. The BDD electrode had good reproducibility: relative standard deviations (RSD) of Cd 2 + and Pb 2 + obtained from 7 replicate experiments were 1.603% and 3.819%, respectively. After comprehensive data comparison of the detection performance for mercury film and BBD electrodes, it was concluded that the BDD electrode could replace mercury film electrodes in insitu monitoring systems, having the advantage of allowing simultaneous detection, being nonpolluting, and able to function for long-durations.

Piezocatalysis has received great attention in recent years. However, despite the great promise therein, high-performance piezocatalysts are still rare and the principles in designing high-performance piezocatalysts remain lacking. We demonstrate here a novel piezocatalyst design by integrating the oxidizing and reducing reaction sites heterojunction on a piezoelectric and conductive matrix. The catalytic composite generates reactive oxidizing species with unprecedented high capabilities. The •O 2 − yield is over 400% that of previously reported catalysts and for the first time realized effective piezocatalytic bactericidal effects over 99%. A range of structural features, including proper energy band alignments, high capacitance, patterned high conductivity, voltage-regulated wettability, and effective piezoelectrical capability, are believed to synergize for their high piezocatalytic performance. This study has extended the piezocatalysts with new design principles, effective descriptors of merits, new applications, and effective performance capabilities.