Qiqi Mao,Wenxin Wang,Kai Deng,Hongjie Yu,Ziqiang Wang,You Xu,Xiaonian Li,Liang Wang,Hongjing Wang
Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts . Herein, we reported a low-content Pt-doped Rh metallene (Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen (H 2 ) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization. Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of −10 mA cm −2 in the hydrogen evolution reaction (HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm −2 in the hydrazine oxidation reaction (HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage (0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm −2 for energy-saving H 2 production, which greatly reduces the electrolysis energy consumption. Moreover, DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d -band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.
In this study, the CNTs were successfully compounded in PbO 2 electrode through composite electrodeposition technology to obtain multi-layer CNT-PbO 2 electrode. Scanning electron microscope , X-ray diffraction and X-ray Photoelectron Spectroscopy were comprehensively used to characterize the lead dioxide electrode and the electrochemical performance were also tested by cyclic voltammetry, and electrochemical impedance spectroscopy. Results showed that CNT-PbO 2 significantly improved the electrochemical performance, which was attributed to that the compound of CNTs in PbO 2 improved the active sites on the surface, with higher oxidation peaks, smaller particle size, larger specific surface area, and lower charge transfer resistance. In the degradation experiment, the chemical oxygen demand removal efficiency of isoniazid by CNT-PbO 2 electrode were 1.37 times of that by pure PbO 2 electrode. The main influence factors on the degradation of ISN, such as initial ISN concentration, Na 2 SO 4 concentration, current density and initial pH value was analyzed in detail. Considered comprehensively the effects of ISN removal efficiency, COD and average current efficiency, the degradation of ISN and COD reached 99.4% and 86.8%, respectively, after the electrode was degraded by electrochemical oxidation for 120 min under the best conditions. In addition, the degradation mechanism of ISN in electrochemical oxidation was studied. According to the intermediate products detected by GC-MS, the possible degradation pathway of ISN in electrochemical oxidation system were proposed.
Ruyi Qian,Tongdong Shen,Qiangqiang Yang,Kun-Yi Andrew Lin,Shaoping Tong
Graphite felt (GF) supported cerium oxide (CeO 2 ) composite was prepared by the impregnation method and used to active persulfate (PS) for degradation of isoniazid (INH). The structure and morphology of the catalyst were characterized by X-ray diffraction, X-ray photoelectron spectrum and scanning electron microscope. The effects of some key parameters including initial PS concentration, initial pH value, catalyst dosage, reaction temperature and inorganic ions on INH degradation were investigated in CeO 2 /GF/PS system. It was found that 94.39% of INH and 89.9% of TOC could be removed within 10 min under the controlled conditions (1.2 g/L CeO 2 /GF, 0.25 g/L PS, initial pH at 6.8 and temperature at 25 ℃). The degradation intermediates of INH were identified by liquid chromatography-mass spectrometry and ion chromatography, and the possible degradation pathway was also proposed. The radical competition tests indicated that hydroxyl radical ( OH), sulfate radical (SO 4 − ), superoxide ( O 2 − ) and singlet oxygen ( 1 O 2 ) coexisted in CeO 2 /GF/PS system, in which OH was the predominated one. The recycling experiment showed the CeO 2 /GF was an excellently stable catalyst for activation of PS.
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