Heterostructures are often constructed to modulate the electronic states of the two catalysts,achieving high-performance in alkaline hydrogen evolution reaction(HER).Various mechanisms have been proposed for the heter...Heterostructures are often constructed to modulate the electronic states of the two catalysts,achieving high-performance in alkaline hydrogen evolution reaction(HER).Various mechanisms have been proposed for the heterostructural catalysts,which however awaits further approvement.Herein,a heterostructure composed of Co_(2)P and CoP was successfully prepared with significantly enhanced HER catalytic activity relative to the endmembers.The ultraviolet photoelectron spectroscopy(UPS)and Xray photoelectron spectroscopy(XPS)revealed the effective promotion of the self-driven transferring of electrons from CoP to Co_(2)P and the accumulation of electrons on the P sites in Co_(2)P due to the strong electronic coupling of built-in electric field in the Co_(2)P/CoP interface.In situ electrochemical impedance spectroscopy(EIS)and poison experiments confirmed the Heyrovsky step of H*intermediate depleting on electronegative P sites and contributions of both metal and P to the reactivity in the Co_(2)P/CoP.Density functional theory(DFT)calculations clarify that the electronic structure at interface of the heterojunction significantly weakens the hydrogen adsorption free energy(ΔGH*ads)of P site in Co_(2)P/CoP to near zero.We also propose an electronic redistribution strategy for heterostructures that activates the multiple routes mechanism and production of more active sites.The working mechanism is expected to be further extended to other transition metal compounds for efficient HER activity.展开更多
Membrane fouling limits the effects of long-term stable operation of membrane bioreactor （MBR）. Control of membrane fouling can extend the membrane life and reduce water treatment cost effectively. A pilot scale ano...Membrane fouling limits the effects of long-term stable operation of membrane bioreactor （MBR）. Control of membrane fouling can extend the membrane life and reduce water treatment cost effectively. A pilot scale anoxic/aerobic-membrane bioreactor （A/O- MBR, 40 L/hr） was used to treat the hyperhaline municipal sewage from a processing zone of Tianjin, China. Impact factors including mixed liquid sludge suspension （MLSS）, sludge viscosity （Ix）, microorganisms, extracellular polymeric substances （EPS）, aeration intensity and suction/suspended time on membrane fouling and pollution control were studied. The relationships among various factors associated with membrane fouling were analyzed. Results showed that there was a positive correlation among MLSS, sludge viscosity and trans-membrane pressure （TMP）. Considering water treatment efficiency and stable operation of the membrane module, MLSS of 5 g/L was suggested for the process. There was a same trend among EPS, sludge viscosity and TMP. Numbers and species of microorganisms affected membrane fouling. Either too high or too low aeration intensity was not conducive to membrane fouling control. Aeration intensity of 1.0 m3/hr （gas/water ratio of 25：1） is suggested for the process. A long suction time caused a rapid increase in membrane resistance. However, long suspended time cannot prevent the increase of membrane resistance effectively even though a suspended time was necessary for scale off particles from the membrane surface. The suction/suspended time of 12 min/3 rain was selected for the process. The interaction of various environmental factors and operation conditions must be considered synthetically.展开更多
基金supported by the fundings from the National Natural Science Foundation of China(Nos.51972210,52111530187,and 82172443)Medical-Engineering Funding of Shanghai Jiao Tong University(No.YG2021QN91).
文摘Heterostructures are often constructed to modulate the electronic states of the two catalysts,achieving high-performance in alkaline hydrogen evolution reaction(HER).Various mechanisms have been proposed for the heterostructural catalysts,which however awaits further approvement.Herein,a heterostructure composed of Co_(2)P and CoP was successfully prepared with significantly enhanced HER catalytic activity relative to the endmembers.The ultraviolet photoelectron spectroscopy(UPS)and Xray photoelectron spectroscopy(XPS)revealed the effective promotion of the self-driven transferring of electrons from CoP to Co_(2)P and the accumulation of electrons on the P sites in Co_(2)P due to the strong electronic coupling of built-in electric field in the Co_(2)P/CoP interface.In situ electrochemical impedance spectroscopy(EIS)and poison experiments confirmed the Heyrovsky step of H*intermediate depleting on electronegative P sites and contributions of both metal and P to the reactivity in the Co_(2)P/CoP.Density functional theory(DFT)calculations clarify that the electronic structure at interface of the heterojunction significantly weakens the hydrogen adsorption free energy(ΔGH*ads)of P site in Co_(2)P/CoP to near zero.We also propose an electronic redistribution strategy for heterostructures that activates the multiple routes mechanism and production of more active sites.The working mechanism is expected to be further extended to other transition metal compounds for efficient HER activity.
基金supported by the Special Projects of Major National Science and Technology of China (No. 2008ZX07314-003)the National Natural Science Foundation of China (No. 50708063)
文摘Membrane fouling limits the effects of long-term stable operation of membrane bioreactor （MBR）. Control of membrane fouling can extend the membrane life and reduce water treatment cost effectively. A pilot scale anoxic/aerobic-membrane bioreactor （A/O- MBR, 40 L/hr） was used to treat the hyperhaline municipal sewage from a processing zone of Tianjin, China. Impact factors including mixed liquid sludge suspension （MLSS）, sludge viscosity （Ix）, microorganisms, extracellular polymeric substances （EPS）, aeration intensity and suction/suspended time on membrane fouling and pollution control were studied. The relationships among various factors associated with membrane fouling were analyzed. Results showed that there was a positive correlation among MLSS, sludge viscosity and trans-membrane pressure （TMP）. Considering water treatment efficiency and stable operation of the membrane module, MLSS of 5 g/L was suggested for the process. There was a same trend among EPS, sludge viscosity and TMP. Numbers and species of microorganisms affected membrane fouling. Either too high or too low aeration intensity was not conducive to membrane fouling control. Aeration intensity of 1.0 m3/hr （gas/water ratio of 25：1） is suggested for the process. A long suction time caused a rapid increase in membrane resistance. However, long suspended time cannot prevent the increase of membrane resistance effectively even though a suspended time was necessary for scale off particles from the membrane surface. The suction/suspended time of 12 min/3 rain was selected for the process. The interaction of various environmental factors and operation conditions must be considered synthetically.
