The objective of this study was to convert biochar,a byproduct generated from the hydrothermal process(in oxygen-limited environment)of biomass(e.g.,corn stover),into value-added product.In specific,three-dimensional(...The objective of this study was to convert biochar,a byproduct generated from the hydrothermal process(in oxygen-limited environment)of biomass(e.g.,corn stover),into value-added product.In specific,three-dimensional(3D)biochar-containing precursor sponge,which was made by using electrospun polymer nanofibers as skeleton support,was fabricated via an innovative approach.The weight ratio of biochar to polymer(in the precursor sponge)was 2/1,and it appeared that the biochar weight ratio could be further increased.Upon heat treatments(i.e.,stabilization in air and carbonization in argon),the precursor sponge was converted into carbon nanofibrous sponge that had the porosity of~90 vol%,the BET surface area of~51.7 m^(2) g^(−1),and the carbon content of~95 wt%;and it was mechanically elastic/resilient.The electrochemical study indicated that,the carbon nanofibrous sponge could be utilized for making supercapacitor electrode with excellent rate capability and high kinetic performance.This study would not only demonstrate a high-value application of hydrothermally generated biochar,but also provide a facile while novel approach for the fabrication of carbon nanofibrous sponge which could be potentially used for various applications(particularly the energy storage application).展开更多
Solar-driven vapor generation by localized solar heating of a photothermal material is an environmentally friendly approach for seawater desalination and wastewater purification.In this work,inspired by the leaf trans...Solar-driven vapor generation by localized solar heating of a photothermal material is an environmentally friendly approach for seawater desalination and wastewater purification.In this work,inspired by the leaf transpiration in nature,we designed a novel bionic leaf to realize highly efficient solar vapor generation.The leaf-inspired three-dimensional(3D)material structure had a hydrophilic polyvinyl alcohol(PVA)foam layer(equivalence to the mesophyll tissue layer in a leaf)with high porosity and low thermal conductivity,a photothermal polypyrrole(PPy)layer(equivalence to the chlorophyll layer in a leaf)coated on the PVA foam,and a micro/nano-scale porous hydrophobic surface layer(equivalence to the stomal layer in a leaf).The PVA network had microchannels for water transportation and reducing water evaporation enthalpy,the PPy layer absorbed and converted solar energy to heat water locally,and the hydrophobic porous surface layer enhanced the rate of vapor escape.The asfabricated vapor generator based on the bionic-leaf structure achieved an impressive high evaporation rate of 3.09 kg m^(−2) h^(−1) under one sun irradiation(1 kW m^(−2)).The prototype vapor generator desalinated and purified brine and seawater successfully under natural sunlight.Such solar vapor generator based on the biomimetic structure provides a potential low-cost and highly efficient water purification technology to help mitigate the global water crisis using sustainable energy.展开更多
基金This research was supported by the Office of Energy Efficiency and Renewable Energy(EERE)in the U.S.Department of Energy(Grant Number:DE-EE0008252).
文摘The objective of this study was to convert biochar,a byproduct generated from the hydrothermal process(in oxygen-limited environment)of biomass(e.g.,corn stover),into value-added product.In specific,three-dimensional(3D)biochar-containing precursor sponge,which was made by using electrospun polymer nanofibers as skeleton support,was fabricated via an innovative approach.The weight ratio of biochar to polymer(in the precursor sponge)was 2/1,and it appeared that the biochar weight ratio could be further increased.Upon heat treatments(i.e.,stabilization in air and carbonization in argon),the precursor sponge was converted into carbon nanofibrous sponge that had the porosity of~90 vol%,the BET surface area of~51.7 m^(2) g^(−1),and the carbon content of~95 wt%;and it was mechanically elastic/resilient.The electrochemical study indicated that,the carbon nanofibrous sponge could be utilized for making supercapacitor electrode with excellent rate capability and high kinetic performance.This study would not only demonstrate a high-value application of hydrothermally generated biochar,but also provide a facile while novel approach for the fabrication of carbon nanofibrous sponge which could be potentially used for various applications(particularly the energy storage application).
基金supported by the Key Project of the Natural Science Foundation of Tianjin(20JCZDJC00350)the National Natural Science Foundation of China(51803108)Tianjin Research Innovation Project for Postgraduate Students(2020YJSB066)。
文摘Solar-driven vapor generation by localized solar heating of a photothermal material is an environmentally friendly approach for seawater desalination and wastewater purification.In this work,inspired by the leaf transpiration in nature,we designed a novel bionic leaf to realize highly efficient solar vapor generation.The leaf-inspired three-dimensional(3D)material structure had a hydrophilic polyvinyl alcohol(PVA)foam layer(equivalence to the mesophyll tissue layer in a leaf)with high porosity and low thermal conductivity,a photothermal polypyrrole(PPy)layer(equivalence to the chlorophyll layer in a leaf)coated on the PVA foam,and a micro/nano-scale porous hydrophobic surface layer(equivalence to the stomal layer in a leaf).The PVA network had microchannels for water transportation and reducing water evaporation enthalpy,the PPy layer absorbed and converted solar energy to heat water locally,and the hydrophobic porous surface layer enhanced the rate of vapor escape.The asfabricated vapor generator based on the bionic-leaf structure achieved an impressive high evaporation rate of 3.09 kg m^(−2) h^(−1) under one sun irradiation(1 kW m^(−2)).The prototype vapor generator desalinated and purified brine and seawater successfully under natural sunlight.Such solar vapor generator based on the biomimetic structure provides a potential low-cost and highly efficient water purification technology to help mitigate the global water crisis using sustainable energy.
