Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for ca...Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for catalyst design and performance improvement in these applications.In this work,we systematically investigate the HPOR/HPRR mechanisms on low-index Pt surfaces,specifically Pt(111),Pt(100)and Pt(110),through density functional theory(DFT)calculations combined with the computational hydrogen electrode(CHE)model.For HPOR,all the low-index Pt surfaces exhibit a unified potential-determining step(PDS)involving the electrochemical oxidation of hydroperoxyl intermediates(HOO*).The binding free energy of HOO*(Δ_(GHOO*))emerges as an activity descriptor,with Pt(110)exhibiting the highest HPOR activity.The HPRR mechanism follows a chem-electrochemical(C-EC)pathway.The rate-determining step(RDS)of HPRR is either the cleavage of the HO-OH bond(chemical)or the reduction of HO(electrochemical),depending on their respective activation energies.These activation energies are functions of the HO*binding free energy,Δ_(GHO*),establishingΔ_(GHO*)as the descriptor for HPRR activity prediction.Pt(111)and Pt(100)are identified as the most active HPRR catalysts among the studied metal surfaces,although they still experience a significant overpotential.The scaling relationship betweenΔ_(GHOO*)andΔ_(GHO*)reveals a thermodynamic coupling of HPOR and HPRR,explaining their occurrence on Pt surfaces.These findings provide important insights and activity descriptors for both HPOR and HPRR,providing valuable guidance for the design of electrocatalysts in H_(2)O_(2)-related energy applications and fuel cells.展开更多
Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow ...Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow operation temperature window.In this study,the trace amounts of Cu are used to modify a Pt/Al_(2)O_(3)catalyst.The introduced Cu_(2+)species are atomically anchored on Pt nanoparticles through strong electrostatic adsorption.展开更多
Treatment of precious metals in electronic waste has attracted tremendous attention and is essential for both environmental protection and resource sustainable development.In this study,a novel adsorbent for precious ...Treatment of precious metals in electronic waste has attracted tremendous attention and is essential for both environmental protection and resource sustainable development.In this study,a novel adsorbent for precious metal ions,V_(2)O_(3)spiny hollow nanospheres(pV_(2)O_(3)SHN),was synthe sized through a one-step hydrothermal-as sis ted methodology for the adsorption of Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ) from the leaching solution of electronic waste.The results reveal that the p-V2O3SHN hierarchy was successfully constructed with a hollow structure and dense spiny morphology.The prepared p-V2O3SHN can effectively remove precious metal ions such as Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ),with the selective capture order being Au(Ⅲ)> Ag(Ⅰ)> Pt(Ⅳ)> Pd(Ⅱ)> other metal ions.This superior adsorption capability can be attributed to the multi-diffusible,intermingled composition,and numerous active sites decorating the p-V2O3SHN hierarchy,facilitating the uptake of Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ) ions from electronic waste.The Langmuir model provided a better fit for the uptake process,revealing maximum uptake capacities of 833.33 mg/g for Au(Ⅲ),370.37 mg/g for Ag(Ⅰ),42.01 mg/g for Pd(Ⅱ),and 77.51 mg/g for Pt(Ⅳ) on p-V_(2)O_(3)SHN.Remarkably,p-V_(2)O_(3)SHN exhibited a robust affinity for the adsorbate due to the presence of surface defects and reduction reactions.The new p-V2O3SHN also demonstrated good reusability for three sorption cycles,highlighting its potential for electronic waste treatment.Due to its facile synthesis and excellent efficiency,hierarchical p-V2O3SHN presents itself as a promising candidate for the selective uptake of Au(Ⅲ),Ag(Ⅰ),Pt(Ⅳ),and Pd(Ⅱ) from electronic waste.展开更多
Graphene has exceptional electrical,optical and thermal properties,and is widely used to create thinner,lighter and faster sensors.In this study,graphene was fabricated by mechanically exfoliating on the SiO_(2)/Si su...Graphene has exceptional electrical,optical and thermal properties,and is widely used to create thinner,lighter and faster sensors.In this study,graphene was fabricated by mechanically exfoliating on the SiO_(2)/Si substrate and the graphene field effect transistor(FET)was prepared by photolithography.Platinum(Pt)particles were doped on the surface of graphene by the hydrazine hydrate reduction method to endow a Pt/graphene sensor with gas-sensing properties.By being tested on a gas detection platform,the characteristics of the electrical(Ⅰ-Ⅴ)curves and resistance response curves were obtained in different hydrogen environments.The results show that the Pt/graphene sensor exhibits a high sensitivity to hydrogen at room temperature,with a resistance response rate of 33.35%at a hydrogen volume fraction of 1.00%.However,the sensitivity lifetime study shows an essential hysteresis in desorption process,which leads to gradually decreases in the resistance response rate.This research provides an improved production method of graphene-based gas sensors,which has a wide range of potential applications in aero-space industry.展开更多
Single-metal sites anchored in nitrogen-doped nanocarbons are recognized as potent electrocatalysts for applications in energy conversion and storage.Here,an innovative inorganic salt-mediated secondary calcination st...Single-metal sites anchored in nitrogen-doped nanocarbons are recognized as potent electrocatalysts for applications in energy conversion and storage.Here,an innovative inorganic salt-mediated secondary calcination strategy was developed to construct robust Pt single-atom catalysts on nitrogen-and oxygen-doped graphene nanosheets(Pt-N/O-GNs),thereby significantly enhancing the efficiency of the electrocatalytic oxygen reduction reaction(ORR).The ultrathin N/O-GNs,obtained by stripping Zn-ZIF with auxiliaries of KCl and LiCl,provide stable anchoring sites for highly exposed Pt-N_(3)O active structures.The Pt-N/O-GNs catalyst,featuring a low Pt loading of 0.44 wt%,demonstrates exceptional mass activity in the ORR process.It attains an impressive onset potential of 0.99 V and a half-wave potential of 0.88 V.The zinc-air battery driven by the Pt-N/O-GNs displays superior power density and cycle stability.Theoretical computational studies reveal that the structure of heteroatoms doped in few-layer graphene facilitates the stable anchoring of single-atom configurations.The findings provide new perspectives for the tailored design and fabrication of single-metal-site electrocatalysts.展开更多
The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing...The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing the amount of Pt would worsen the problems caused by the adsorption of perfluorinated sulfonic acid(PFSA)ionomers to Pt via the side chains,namely,blocking the active sites of Pt and inducing densely packed layers of fluorocarbon backbones on Pt surface to obstruct local O_(2)transport at the Pt/PFSA interfaces.This work aims at optimizing the Pt/ionomer interface to mitigate the sulfonate adsorption and in the meantime to reduce the local O_(2)transport resistance(R_(local)),by using a porous composite of 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid(IL)modified MOF-808(BMImHSO_(4)@MOF-808)as additive in cathodic catalyst layer(CCL).Through detailed physical,spectroscopic and electrochemical characterizations,we demonstrate a three-fold optimization mechanism of Pt/ionomer interface structure by BMImHSO_(4)@MOF-808:the unsaturated metal sites in MOF-808 effectively inhibit the sulfonate adsorption on Pt through coordination with the sulfonates of PFSA,thereby improving catalyst utilization;the pores in MOF-808 establish efficient transport channels for gaseous oxygen,significantly reducing R_(local);the IL modification layers facilitate the formation of continuous proton transport networks,increasing proton conductivity.The incorporation of BMImHSO_(4)@MOF-808 in a low-Pt CCL(0.1 mg_(Pt)cm^(-2))yields a peak power density of 1.9 W cm^(-2)for PEMFC under H_(2)-O_(2)condition,and ca.20%increase of power density under H_(2)-air condition as compared with conventional CCL,indicating the prospect of IL-MOF composites as an efficient additive to enhance the performance of PEMFCs.展开更多
基金Supported by the Shanxi Province Grant(202203021212007,2023SHB003).
文摘Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for catalyst design and performance improvement in these applications.In this work,we systematically investigate the HPOR/HPRR mechanisms on low-index Pt surfaces,specifically Pt(111),Pt(100)and Pt(110),through density functional theory(DFT)calculations combined with the computational hydrogen electrode(CHE)model.For HPOR,all the low-index Pt surfaces exhibit a unified potential-determining step(PDS)involving the electrochemical oxidation of hydroperoxyl intermediates(HOO*).The binding free energy of HOO*(Δ_(GHOO*))emerges as an activity descriptor,with Pt(110)exhibiting the highest HPOR activity.The HPRR mechanism follows a chem-electrochemical(C-EC)pathway.The rate-determining step(RDS)of HPRR is either the cleavage of the HO-OH bond(chemical)or the reduction of HO(electrochemical),depending on their respective activation energies.These activation energies are functions of the HO*binding free energy,Δ_(GHO*),establishingΔ_(GHO*)as the descriptor for HPRR activity prediction.Pt(111)and Pt(100)are identified as the most active HPRR catalysts among the studied metal surfaces,although they still experience a significant overpotential.The scaling relationship betweenΔ_(GHOO*)andΔ_(GHO*)reveals a thermodynamic coupling of HPOR and HPRR,explaining their occurrence on Pt surfaces.These findings provide important insights and activity descriptors for both HPOR and HPRR,providing valuable guidance for the design of electrocatalysts in H_(2)O_(2)-related energy applications and fuel cells.
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3504200)the National Natural Science Foundation of China(Nos.U21A20326 and 22376063)+4 种基金the fund of the National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2020A05)the Fundamental Research Funds for the Central Universitiesthe funding received from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 897197.Y.L.(CSC No.202006740085)is grateful for thegrant from the China Scholarship Councilthe ICREA Academia program and grants MICINN/FEDER PID2021124572OB-C31 and GC 2021 SGR 01061part of Maria de Maeztu Units of Excellence Programme CEX2023-001300-M/funded by MCIN/AEI/https://doi.org/10.13039/501100011033
文摘Preferential oxidation of CO(CO-PROX)in H_(2)-rich streams is highly important for purifying the industrial grade H_(2)used in proton-exchange-membrane fuel cells(PEMFC),but it is still limited to a relatively narrow operation temperature window.In this study,the trace amounts of Cu are used to modify a Pt/Al_(2)O_(3)catalyst.The introduced Cu_(2+)species are atomically anchored on Pt nanoparticles through strong electrostatic adsorption.
基金supported by the Open Project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.ES202306).
文摘Treatment of precious metals in electronic waste has attracted tremendous attention and is essential for both environmental protection and resource sustainable development.In this study,a novel adsorbent for precious metal ions,V_(2)O_(3)spiny hollow nanospheres(pV_(2)O_(3)SHN),was synthe sized through a one-step hydrothermal-as sis ted methodology for the adsorption of Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ) from the leaching solution of electronic waste.The results reveal that the p-V2O3SHN hierarchy was successfully constructed with a hollow structure and dense spiny morphology.The prepared p-V2O3SHN can effectively remove precious metal ions such as Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ),with the selective capture order being Au(Ⅲ)> Ag(Ⅰ)> Pt(Ⅳ)> Pd(Ⅱ)> other metal ions.This superior adsorption capability can be attributed to the multi-diffusible,intermingled composition,and numerous active sites decorating the p-V2O3SHN hierarchy,facilitating the uptake of Au(Ⅲ),Ag(Ⅰ),Pd(Ⅱ),and Pt(Ⅳ) ions from electronic waste.The Langmuir model provided a better fit for the uptake process,revealing maximum uptake capacities of 833.33 mg/g for Au(Ⅲ),370.37 mg/g for Ag(Ⅰ),42.01 mg/g for Pd(Ⅱ),and 77.51 mg/g for Pt(Ⅳ) on p-V_(2)O_(3)SHN.Remarkably,p-V_(2)O_(3)SHN exhibited a robust affinity for the adsorbate due to the presence of surface defects and reduction reactions.The new p-V2O3SHN also demonstrated good reusability for three sorption cycles,highlighting its potential for electronic waste treatment.Due to its facile synthesis and excellent efficiency,hierarchical p-V2O3SHN presents itself as a promising candidate for the selective uptake of Au(Ⅲ),Ag(Ⅰ),Pt(Ⅳ),and Pd(Ⅱ) from electronic waste.
基金National Natural Science Foundation of China(No.51905090)。
文摘Graphene has exceptional electrical,optical and thermal properties,and is widely used to create thinner,lighter and faster sensors.In this study,graphene was fabricated by mechanically exfoliating on the SiO_(2)/Si substrate and the graphene field effect transistor(FET)was prepared by photolithography.Platinum(Pt)particles were doped on the surface of graphene by the hydrazine hydrate reduction method to endow a Pt/graphene sensor with gas-sensing properties.By being tested on a gas detection platform,the characteristics of the electrical(Ⅰ-Ⅴ)curves and resistance response curves were obtained in different hydrogen environments.The results show that the Pt/graphene sensor exhibits a high sensitivity to hydrogen at room temperature,with a resistance response rate of 33.35%at a hydrogen volume fraction of 1.00%.However,the sensitivity lifetime study shows an essential hysteresis in desorption process,which leads to gradually decreases in the resistance response rate.This research provides an improved production method of graphene-based gas sensors,which has a wide range of potential applications in aero-space industry.
文摘Single-metal sites anchored in nitrogen-doped nanocarbons are recognized as potent electrocatalysts for applications in energy conversion and storage.Here,an innovative inorganic salt-mediated secondary calcination strategy was developed to construct robust Pt single-atom catalysts on nitrogen-and oxygen-doped graphene nanosheets(Pt-N/O-GNs),thereby significantly enhancing the efficiency of the electrocatalytic oxygen reduction reaction(ORR).The ultrathin N/O-GNs,obtained by stripping Zn-ZIF with auxiliaries of KCl and LiCl,provide stable anchoring sites for highly exposed Pt-N_(3)O active structures.The Pt-N/O-GNs catalyst,featuring a low Pt loading of 0.44 wt%,demonstrates exceptional mass activity in the ORR process.It attains an impressive onset potential of 0.99 V and a half-wave potential of 0.88 V.The zinc-air battery driven by the Pt-N/O-GNs displays superior power density and cycle stability.Theoretical computational studies reveal that the structure of heteroatoms doped in few-layer graphene facilitates the stable anchoring of single-atom configurations.The findings provide new perspectives for the tailored design and fabrication of single-metal-site electrocatalysts.
文摘The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing the amount of Pt would worsen the problems caused by the adsorption of perfluorinated sulfonic acid(PFSA)ionomers to Pt via the side chains,namely,blocking the active sites of Pt and inducing densely packed layers of fluorocarbon backbones on Pt surface to obstruct local O_(2)transport at the Pt/PFSA interfaces.This work aims at optimizing the Pt/ionomer interface to mitigate the sulfonate adsorption and in the meantime to reduce the local O_(2)transport resistance(R_(local)),by using a porous composite of 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid(IL)modified MOF-808(BMImHSO_(4)@MOF-808)as additive in cathodic catalyst layer(CCL).Through detailed physical,spectroscopic and electrochemical characterizations,we demonstrate a three-fold optimization mechanism of Pt/ionomer interface structure by BMImHSO_(4)@MOF-808:the unsaturated metal sites in MOF-808 effectively inhibit the sulfonate adsorption on Pt through coordination with the sulfonates of PFSA,thereby improving catalyst utilization;the pores in MOF-808 establish efficient transport channels for gaseous oxygen,significantly reducing R_(local);the IL modification layers facilitate the formation of continuous proton transport networks,increasing proton conductivity.The incorporation of BMImHSO_(4)@MOF-808 in a low-Pt CCL(0.1 mg_(Pt)cm^(-2))yields a peak power density of 1.9 W cm^(-2)for PEMFC under H_(2)-O_(2)condition,and ca.20%increase of power density under H_(2)-air condition as compared with conventional CCL,indicating the prospect of IL-MOF composites as an efficient additive to enhance the performance of PEMFCs.
