Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing mu...Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing multifunctional composite material.In this paper,a kind of polyaniline@CNF/polyvinyl alcohol-H_(2)SO_(4) multifunctional composite material(PANI@CNF/PVA-H_(2)SO_(4))was successfully designed by in-situ chemical polymerization of conductive polyaniline(PANI)onto CNF aerogel with high aspect ratio,and then coated with PVA-H_(2)SO_(4) gel.The composite material has a specific capacitance of 502.2 F/g at a scan rate of 5 mV/s as supercapacitor electrode.Furthermore,when the composite was assembled into a symmetrical supercapacitor,it can still provide an energy density of 11.49 W·h/kg at a high power density of 413.55 W/kg.Besides,the as-obtained PANI@CNF/PVA-H_(2)SO_(4) composite has an excellent electromagnetic shielding performance of 34.75 dB in X-band.In addition,due to the excellent flexibility of CNF and PVA,the PANI@CNF/PVA-H2SO4 composites can be further applied to stress sensors to detect pressure and human motion signals.展开更多
Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostru...Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostructures are the most promising class of non-precious metal catalysts （NPMCs） with satisfactory activities and stabilities in practical fuel cell applications. However, the long-debated nature of the active sites and the elusive structure-performance correlation impede further developments of M-N/C materials. In this review, we present recent endeavors to elucidate the actual structures of active sites by adopting a variety of physicochemical techniques that may provide a profound mechanistic understanding of M-N/C catalysts. Then, we focus on the spectacular progress in structural optimization strategies for M-N/C materials with tailored precursor architectures and modified synthetic routes for controlling the structural uniformity and maximizing the number of active sites in catalytic materials. The recognition of the right active centers and site-specific engineering of the nanostructures provides future directions for designing advantageous M-N/C catalysts.展开更多
基金supported by the fund of National Natural Science Foundation of China(22078184,22378249 and 22178208)Key R&D Plan of Shaanxi Province(2024GX-YBXM-335)+1 种基金China Postdoctoral Science Foundation(2019M653853XB)Natural science advance research foundation of Shaanxi University of Science and Technology(2018QNBJ-03).
文摘Recently,multifunctional materials have received widespread attention from researchers.Cellulose nanofibers(CNF)is one of biomass materials with abundant hydroxyl groups,which shows great potential in manufacturing multifunctional composite material.In this paper,a kind of polyaniline@CNF/polyvinyl alcohol-H_(2)SO_(4) multifunctional composite material(PANI@CNF/PVA-H_(2)SO_(4))was successfully designed by in-situ chemical polymerization of conductive polyaniline(PANI)onto CNF aerogel with high aspect ratio,and then coated with PVA-H_(2)SO_(4) gel.The composite material has a specific capacitance of 502.2 F/g at a scan rate of 5 mV/s as supercapacitor electrode.Furthermore,when the composite was assembled into a symmetrical supercapacitor,it can still provide an energy density of 11.49 W·h/kg at a high power density of 413.55 W/kg.Besides,the as-obtained PANI@CNF/PVA-H_(2)SO_(4) composite has an excellent electromagnetic shielding performance of 34.75 dB in X-band.In addition,due to the excellent flexibility of CNF and PVA,the PANI@CNF/PVA-H2SO4 composites can be further applied to stress sensors to detect pressure and human motion signals.
文摘Accelerating the rate-limiting oxygen reduction reaction （ORR） at the cathode remains the foremost issue for the commercialization of fuel cells. Transition metal-nitrogen-carbon （M-N/C, M = Fe, Co, etc.） nanostructures are the most promising class of non-precious metal catalysts （NPMCs） with satisfactory activities and stabilities in practical fuel cell applications. However, the long-debated nature of the active sites and the elusive structure-performance correlation impede further developments of M-N/C materials. In this review, we present recent endeavors to elucidate the actual structures of active sites by adopting a variety of physicochemical techniques that may provide a profound mechanistic understanding of M-N/C catalysts. Then, we focus on the spectacular progress in structural optimization strategies for M-N/C materials with tailored precursor architectures and modified synthetic routes for controlling the structural uniformity and maximizing the number of active sites in catalytic materials. The recognition of the right active centers and site-specific engineering of the nanostructures provides future directions for designing advantageous M-N/C catalysts.
