Hindering the recombination of a photogenerated carrier is a crucial method to enhance the photoelectrochemical performance of ZnO due to its high exciton binding energy. Herein, the intramolecular donor−acceptor compensated semiconductor ZnO (I-D/A ZnO), introducing C dopants and oxygen vacancies, was prepared with the assistance of ascorbic acid (AA). According to the DFT calculations, the asymmetry DOS could lead to the longer carrier lifetime and the smaller electron transfer resistance. Then, the photoelectrochemical biosensor toward glucose was regarded as a model to discuss the application of ZnO in biosensors. As a result, the biosensor based on I-D/A ZnO showed good performance with high sensitivity, low limit of detection, and fine anti-interference, meaning that I-D/A ZnO is a promising semiconductor for photoelectrochemical biosensors.
In this study, the effect on the structure stability, elastic properties and electronic structure of P-doped Mg 2 Si were studied by the first-principles pseudopotential plane wave method based on density functional theory. The lattice constants, formation enthalpy, cohesive energy, elastic constants, and elastic moduli of Mg 2 Si, Mg 7 Si 4 P, Mg 8 Si 3 P and Mg 8 Si 4 P were calculated, and the electronic structure analysis was also performed. The occupation tendency, structural stability, bonding characteristics, orbital hybridization and the change of conductivity of doping P atoms in the matrix were further investigated. Among them, the research results of formation enthalpy, cohesive energy and elastic constant show that Mg 2 Si, Mg 8 Si 3 P and Mg 8 Si 4 P can all exist stably in the system, and the crystal structure of Mg 7 Si 4 P can not exist stably. P atoms doping into the Mg 2 Si lattice tend to occupy Si atoms position preferentially. The results of elastic modulus study show that Mg 2 Si and Mg 8 Si 4 P are brittle phase and Mg 8 Si 3 P is ductile phase. The plasticity and toughness of Mg 2 Si alloy system are improved by doping P atoms. The electronic structure analysis shows that the method of doping P atoms changes the orbital hybridization and bonding characteristics of the system. The Mg-P and Si-P covalent bond formed by Mg 8 Si 3 P and Mg 8 Si 4 P increase the structure stability. The energy band structure analysis also show reduction of the band gap from 0.224 to 0.184 eV for Mg 2 Si with P dopants at the substitutional Si-sites and the band gap closure in the system with interstitial P-impurities. It enhances the metallic property of the material, and Mg 8 Si 4 P phase also transform from its semiconducting to metallic state. Consequently, this method both increases the carrier concentration and reduces the energy of free electron transition. The conductivity of the Mg 2 Si alloy system will be improve.
Paper has become one of the most promising substrates for building low‐cost and powerful sensing platforms due to its self‐pumping ability and compatibility with multiple patterning methods. Paper‐based sensors have been greatly developed in the field of environmental monitoring. In this review, we introduced the research and application of paper‐based sensors in environmental monitoring, focusing on the deposition and patterning methods of building paper‐based sensors, and summarized the applications of detecting environmental pollutants, including metal ions, anions, explosives, neurotoxins, volatile organic compounds, and small molecules. In addition, the development prospects and challenges of promoting paper‐based sensors are also discussed. The current review will provide references for the construction of portable paper‐based sensors, and has implications for the field of on‐site real‐time detection of the environment.
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