Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5...Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5)P_(4)catalysts on nickel foam with efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performance in alkaline media.Density Functional Theory(DFT)calculations and experimental studies have shown that Mo doping deadeneds the interaction between H and O atomic orbitals of transition state water molecules,effectively weakening the activation energy of H_(2)O dissociation.Therefore,Mo doping is favorable for enhancing HER activity with overpotential at 10 mA cm^(-2)of 93 mV and Tafel slope of 40.1 mV dec^(-1)in 1 M KOH.Besides,it exhibits high alkaline OER activity with an ultra-low overpotential of 200 mV at 10 mA cm^(-2).Moreover,this catalyst only needs 1.537 V in a dual-electrode configuration of the electrolytic cell,which is much lower than the commercial Pt/C-RuO_(2)couple(1.614 V).In addition,we have developed and constructed a solar thermoelectric generator(TEG)that is capable of floating on water.This TEG has a continuous power output and an exceptionally long lifespan,providing a stable power supply to the synthesized catalyst electrolyzer.It can produce a maximum power output of over 90 mW,meeting the requirement of converting solar radiation heat into usable electricity.As a result,the system achieves productivity of 0.11 mL min^(-1)H_(2).This solar thermal energy conversion technology shows the possibility of large-scale industrial production of H_(2)and provides a new idea for exploring heat source utilization.展开更多
There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresse...There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.展开更多
Carbon materials loaded with single-atom catalysts(SACs) exhibit significant potential for catalyzing sulfur redox reactions and inhibiting polysulfide shuttling effects.However,traditional single-atom structures with...Carbon materials loaded with single-atom catalysts(SACs) exhibit significant potential for catalyzing sulfur redox reactions and inhibiting polysulfide shuttling effects.However,traditional single-atom structures with nitrogen coordination face limitations in addressing the challenges of lithium-sulfur(Li-S) batteries,as the strong electronegativity of nitrogen diminishes the activity of catalytic sites.Herein,a Co single-atom graphene-like carbon nanosheet with both nitrogen and phosphorus coordination is synthesized(Co-N_(2)P_(2)/C).Both experimental and theoretical studies reveal that the Co-N_(2)P_(2)single-atom structure exhibits enhanced capabilities for adsorbing lithium polysulfides and catalyzing their bidirectional conversion.The introduction of phosphorus induces an asymmetric shift in the electronic structure of the single atom,optimizing electron transport.The layered structure of the nanosheets provides an exceptionally high specific surface area,facilitating the exposure of catalytic sites.Furthermore,the S/Co-N_(2)P_(2)/C soft-packed battery retained a weight energy density of 334 Wh·kg^(-1)after 100cycles,demonstrating its practical application value.This research offers valuable guidance for advancing efficient SACs in Li-S battery development.展开更多
The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization mo...The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization model of spinel was established to calculate the effects of basicity(the mass ratio of CaO to SiO_(2))and P_(2)O_(5) on crystal growth rates and precipitation patterns.Based on the crystal size distribution(CSD)theory,the size distribution and growth mechanisms of spinel crystals in alkaline vanadium slag at different temperatures were investigated.The results revealed that,at a cooling rate of 5 K/min,the mean grain size of spinel increased from 12.77 to 21.52μm as the temperature decreased from 1748 to 1598 K,with spinel growth being controlled by the interface.At 1548 K,the spinel particle size reached 31.04μm,indicating a supply-controlled growth mechanism as the temperature decreased from 1598 to 1548 K.Increased P_(2)O_(5) content hindered the crystal growth,while an increase in basicity promoted nucleation and growth.Furthermore,MnCr_(2)O_(4) preferentially crystallized and grew in alkaline vanadium slag.展开更多
基金supported by the Hainan Provincial Natural Science Foundation of China(Nos.522MS038 and 522QN282)the National Natural Science Foundation of China(Nos.52172086 and 52301268)the Start-up Research Foundation of Hainan University(No.KYQD(ZR)-22019).
文摘Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5)P_(4)catalysts on nickel foam with efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performance in alkaline media.Density Functional Theory(DFT)calculations and experimental studies have shown that Mo doping deadeneds the interaction between H and O atomic orbitals of transition state water molecules,effectively weakening the activation energy of H_(2)O dissociation.Therefore,Mo doping is favorable for enhancing HER activity with overpotential at 10 mA cm^(-2)of 93 mV and Tafel slope of 40.1 mV dec^(-1)in 1 M KOH.Besides,it exhibits high alkaline OER activity with an ultra-low overpotential of 200 mV at 10 mA cm^(-2).Moreover,this catalyst only needs 1.537 V in a dual-electrode configuration of the electrolytic cell,which is much lower than the commercial Pt/C-RuO_(2)couple(1.614 V).In addition,we have developed and constructed a solar thermoelectric generator(TEG)that is capable of floating on water.This TEG has a continuous power output and an exceptionally long lifespan,providing a stable power supply to the synthesized catalyst electrolyzer.It can produce a maximum power output of over 90 mW,meeting the requirement of converting solar radiation heat into usable electricity.As a result,the system achieves productivity of 0.11 mL min^(-1)H_(2).This solar thermal energy conversion technology shows the possibility of large-scale industrial production of H_(2)and provides a new idea for exploring heat source utilization.
文摘There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.
基金financially supported by the National Natural Science Foundation of China(Nos.52271011 and 52102291)
文摘Carbon materials loaded with single-atom catalysts(SACs) exhibit significant potential for catalyzing sulfur redox reactions and inhibiting polysulfide shuttling effects.However,traditional single-atom structures with nitrogen coordination face limitations in addressing the challenges of lithium-sulfur(Li-S) batteries,as the strong electronegativity of nitrogen diminishes the activity of catalytic sites.Herein,a Co single-atom graphene-like carbon nanosheet with both nitrogen and phosphorus coordination is synthesized(Co-N_(2)P_(2)/C).Both experimental and theoretical studies reveal that the Co-N_(2)P_(2)single-atom structure exhibits enhanced capabilities for adsorbing lithium polysulfides and catalyzing their bidirectional conversion.The introduction of phosphorus induces an asymmetric shift in the electronic structure of the single atom,optimizing electron transport.The layered structure of the nanosheets provides an exceptionally high specific surface area,facilitating the exposure of catalytic sites.Furthermore,the S/Co-N_(2)P_(2)/C soft-packed battery retained a weight energy density of 334 Wh·kg^(-1)after 100cycles,demonstrating its practical application value.This research offers valuable guidance for advancing efficient SACs in Li-S battery development.
基金supported by the National Natural Science Foundation of China(No.51974047)the Natural Science Foundation of Chongqing,China(No.cstc2022ycjh-bgzxm0003)the Large Instrument Foundation of Chongqing University,China(No.202303150239)。
文摘The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization model of spinel was established to calculate the effects of basicity(the mass ratio of CaO to SiO_(2))and P_(2)O_(5) on crystal growth rates and precipitation patterns.Based on the crystal size distribution(CSD)theory,the size distribution and growth mechanisms of spinel crystals in alkaline vanadium slag at different temperatures were investigated.The results revealed that,at a cooling rate of 5 K/min,the mean grain size of spinel increased from 12.77 to 21.52μm as the temperature decreased from 1748 to 1598 K,with spinel growth being controlled by the interface.At 1548 K,the spinel particle size reached 31.04μm,indicating a supply-controlled growth mechanism as the temperature decreased from 1598 to 1548 K.Increased P_(2)O_(5) content hindered the crystal growth,while an increase in basicity promoted nucleation and growth.Furthermore,MnCr_(2)O_(4) preferentially crystallized and grew in alkaline vanadium slag.
