The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influen...The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influenced by the morphology of the support.Hydrothermal synthesis was employed to produce different morphologies ofγ-Al_(2)O_(3):flower-likeγ-Al_(2)O_(3)(f)exposing(110)crystal faces,sheet-likeγ-Al_(2)O_(3)(s)revealing(100)crystal faces,and rod-likeγ-Al_(2)O_(3)(r)displaying(111)crystal faces,followed by loading PtCo nanoparticles.The exposed crystal faces of the support impact the alloying degree of the PtCo nanoparticles,and an increase in the alloying degree correlates with enhanced catalyst reactivity.Pt_(3)Co intermetallic compounds were identified onγ-Al_(2)O_(3)(f)exposing(110)crystal faces,and PtCo/γ-Al_(2)O_(3)(f)showed high catalytic activity in the CO-PROX reaction,achieving 100%CO conversion across a broad temperature range of 50−225°C.In contrast,only partial alloying of PtCo was observed onγ-Al_(2)O_(3)(s).Furthermore,no alloying between Pt and Co occurred in PtCo/γ-Al_(2)O_(3)(r),resulting in a reaction rate at 50°C that was merely 11%of that of PtCo/γ-Al_(2)O_(3)(f).The formation of Pt3Co intermetallic compounds led to a more oxidized state of Pt,which significantly diminished the adsorption of CO on Pt and augmented the active oxygen species,thereby facilitating the selective oxidation of CO.展开更多
Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Stra...Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Strain engineering is widely employed to tune Pt-M catalysts,but its impact on the structure-property relationship is often interwoven with multiple factors.In this work,we propose a bi-stage strain tuning method and demonstrate it on the most common PtCo catalysts.Macro-strain is introduced by synthesizing single-crystal PtCo nanodendrites,whereas mild acid etching introduces micro-strain to the surface.The half-wave potential of as-treated catalysts reaches 0.959 V,and mass activity is up to 0.69 A mg^(−1)_(Pt).A minimal decrease of 2 mV is observed for half-wave potential after 10,000 cycles.Detailed analysis using advanced transmission electron microscopy,wide-angle X-ray scattering,etc.provides direct evidence that surface disorder at the atomic scale accounts for the enhanced activity and stability.In contrast,the simplicity of this approach allows for scaling up on Pt-M catalysts,as demonstrated on PEMFCs.The bi-stage strain tuning strategy provides a new perspective and reference for improving the activity and durability of Pt-M catalysts.展开更多
The high activity and stability of intermetallic PtCo nanocatalysts toward oxygen reduction reaction make them a top candidate as low-Pt cathode catalysts in proton exchange membrane fuel cells(PEMFCs).However,forming...The high activity and stability of intermetallic PtCo nanocatalysts toward oxygen reduction reaction make them a top candidate as low-Pt cathode catalysts in proton exchange membrane fuel cells(PEMFCs).However,forming intermetallic structures typically requires high-temperature annealing,posing a challenge for achieving well-size control and highly ordered structures.Here we report the design and synthesis of bimetallic co re@shell structured precursors for affording high-performance intermetallic PtCo catalysts.The fabrication of the core@shell precursor involves using a molecular ligand containing both sulfur and oxygen donors to selectively bind with Pt colloidal nanoparticles as the core and chelate Co ions as the shell.During high-temperature annealing,the ligand transforms into carbon coatings around alloy nanoparticles,preventing particle sintering;meanwhile,Co ions in the shell can easily diffuse into the Pt core,which helps to increase the thermodynamic driving force for forming intermetallic structures.These benefits enable us to obtain the catalyst with finely dispersed nanoparticles(~3.5 nm)and a high ordering degree of 72%.With 0.1 mgPt/cm^(2)cathode loading,the catalyst delivers superior performance and durability in PEMFCs,showing an initial mass activity of 0.56 A/mgPt,an initial power density of 1.05 W/cm^(2)at 0.67 V(H_(2)-air),and a voltage loss of 26 mV at 0.8 A/cm^(2)after the accelerated durability test.展开更多
Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilizati...Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilization efficiency and durability by doping non-noble metals to form Pt-based alloy catalysts.Alloying Pt with Co has been recognized as one of the most effective approaches to achieve this goal.PtCo bimetal combination is one of the most promising candidates to synthesize highly efficient catalysts for oxygen reduction reaction(ORR)applications,owing to its relatively more suitable oxygen binding energy for four-electron transfer reactions.Recently,impressive strategies have been developed to fabricate more active and stable PtCo-based multimetallic alloys with tailorable size and morphology.This paper aims to summarize the most recent highlights on the study of the relationship between preparation strategies,morphologies,electroactivities of the PtCo-based catalyst at atomic level and further the relevant reaction mechanism.The challenges and opportunities on the further development of electrocatalysts for fuel cells are included to provide reference for the practical application.展开更多
The methanol oxidation reaction is a critical half-reaction in direct methanol fuel cells(DMFCs),but its efficiency is limited by the low activity and poor stability of traditional electrocatalysts.This study reports ...The methanol oxidation reaction is a critical half-reaction in direct methanol fuel cells(DMFCs),but its efficiency is limited by the low activity and poor stability of traditional electrocatalysts.This study reports the development of a high-performance PtCo/Mo_(2)CT_(x)catalyst for methanol oxidation in DMFCs.Synthesized by depositing PtCo alloy nanoparticles on Mo_(2)CT_(x)sheets prepared via cetyltrimethylammonium bromide-assisted etching of Mo2Ga2C,the PtCo/Mo_(2)CT_(x)catalyst achieved enhanced interlayer spacing and excellent dispersion of active sites.The optimized PtCo/Mo_(2)CT_(x)catalyst exhibited remarkable catalytic activity,reaching a mass activity of 2296 mA·mg_(Pt)^(-1)—6.5 times that of commercial Pt/C.Electrochemical studies confirmed the catalyst's low charge transfer resistance,high electrochemical surface area,and strong CO antipoisoning ability.Stability tests showed that the catalyst retained 62.26%activity after 1000 cycles.These improvements are attributed to the synergistic effects between Pt and Co,the conductive and layered structure of Mo_(2)CT_(x),making PtCo/Mo_(2)CT_(x)a promising,durable anode material for DMFCs in sustainable energy applications.展开更多
Nanotwinned materials possess exceptional properties and represent a promising class of metastable materials.However,their controlled synthesis remains challenging.Here,we report the synthesis of twinned PtCo nanopart...Nanotwinned materials possess exceptional properties and represent a promising class of metastable materials.However,their controlled synthesis remains challenging.Here,we report the synthesis of twinned PtCo nanoparticles via a laser ablation approach,which promotes the formation of unique nanostructures.By optimizing laser parameters such as power and exposure time,we achieved a nanotwinning yield up to 61%,significantly higher than 12%in commercial PtCo.In proton-exchange membrane fuel cell tests,the nanotwinned PtCo catalyst demonstrated a mass activity of 0.56 A·mgPt^(-1) with 82.1%retention after accelerated stress testing.Notably,the voltage loss at 1 A·cm^(-2) was only 24.3 mV.Particle agglomeration and the reduction of stacking fault energy through alloying were identified as possible mechanisms for nanotwin formation.This work provides an efficient and rapid route for the controlled synthesis of nanotwinned particles,and the approach could potentially enable scalable production of high-performance catalysts.展开更多
The development of low-cost,highly active platinum(Pt)-based electrocatalysts for oxygen reduction reaction(ORR)is crucial for widespread applications of fuel cells.An effective approach lies in alloying Pt with non-n...The development of low-cost,highly active platinum(Pt)-based electrocatalysts for oxygen reduction reaction(ORR)is crucial for widespread applications of fuel cells.An effective approach lies in alloying Pt with non-noble transition metals to modulate the physicochemical state of the Pt surface.However,fundamental challenges remain in understanding the structure-performance relationship due to the complexity of composition,crystal type,and surface structure during the alloying process.In this study,we synthesized a series of PtCo bimetallic solid solutions with varying ratios using a liquid-phase synthesis method.By exploiting the characteristics of solid solutions,the resulting PtCo bimetallic alloy maintains the face-centered cubic crystal structure of pure platinum,minimizing the complexities introduced during alloying and facilitating mechanism analysis.Furthermore,under controlled alloy composition and crystal structure,we investigated the dependence of the electrocatalytic activity for the oxygen reduction reaction on the surface strain of the platinum catalyst.The S-PtCo-SNPs cathode designed accordingly endows both proton exchange membrane fuel cell(PEMFC)(2.08 W cm^(−2) at 4 A cm^(−2))and Zn-air battery(ZAB)(143.1 mW cm^(−2) at 214.5 mA cm^(−2))with outstanding performance.展开更多
基金supported by the National Natural Science Foundation of China(22376063,21976057)the Fund of the National Engineering Laboratory for Mobile Source Emission Control Technology(NELMS2020A05)Fundamental Research Funds for the Central Universities.
文摘The preferential oxidation of CO(CO-PROX)reaction is a cost-effective method for eliminating trace amounts of CO from the fuel H2.Pt-based catalysts have been extensively studied for COPROX,with their activity influenced by the morphology of the support.Hydrothermal synthesis was employed to produce different morphologies ofγ-Al_(2)O_(3):flower-likeγ-Al_(2)O_(3)(f)exposing(110)crystal faces,sheet-likeγ-Al_(2)O_(3)(s)revealing(100)crystal faces,and rod-likeγ-Al_(2)O_(3)(r)displaying(111)crystal faces,followed by loading PtCo nanoparticles.The exposed crystal faces of the support impact the alloying degree of the PtCo nanoparticles,and an increase in the alloying degree correlates with enhanced catalyst reactivity.Pt_(3)Co intermetallic compounds were identified onγ-Al_(2)O_(3)(f)exposing(110)crystal faces,and PtCo/γ-Al_(2)O_(3)(f)showed high catalytic activity in the CO-PROX reaction,achieving 100%CO conversion across a broad temperature range of 50−225°C.In contrast,only partial alloying of PtCo was observed onγ-Al_(2)O_(3)(s).Furthermore,no alloying between Pt and Co occurred in PtCo/γ-Al_(2)O_(3)(r),resulting in a reaction rate at 50°C that was merely 11%of that of PtCo/γ-Al_(2)O_(3)(f).The formation of Pt3Co intermetallic compounds led to a more oxidized state of Pt,which significantly diminished the adsorption of CO on Pt and augmented the active oxygen species,thereby facilitating the selective oxidation of CO.
基金the National Natural Science Foundation of China(NO.12274010,12474003)Beijing Nova Program(20240484584)+2 种基金the support from the Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(No.22dz2260800)the Shanghai Science and Technology Committee,China(No.22JC1410300)the National Natural Science Foundation of China(No.52103330)。
文摘Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Strain engineering is widely employed to tune Pt-M catalysts,but its impact on the structure-property relationship is often interwoven with multiple factors.In this work,we propose a bi-stage strain tuning method and demonstrate it on the most common PtCo catalysts.Macro-strain is introduced by synthesizing single-crystal PtCo nanodendrites,whereas mild acid etching introduces micro-strain to the surface.The half-wave potential of as-treated catalysts reaches 0.959 V,and mass activity is up to 0.69 A mg^(−1)_(Pt).A minimal decrease of 2 mV is observed for half-wave potential after 10,000 cycles.Detailed analysis using advanced transmission electron microscopy,wide-angle X-ray scattering,etc.provides direct evidence that surface disorder at the atomic scale accounts for the enhanced activity and stability.In contrast,the simplicity of this approach allows for scaling up on Pt-M catalysts,as demonstrated on PEMFCs.The bi-stage strain tuning strategy provides a new perspective and reference for improving the activity and durability of Pt-M catalysts.
基金the funding support from the National Natural Science Foundation of China(Grants 22325903,22221003,and 22071225)the National Key Research and Development Program of China(Grant 2018YFA0702001)+1 种基金the Plan for Anhui Major Provincial Science&Technology Project(Grants 202203a0520013 and 2021d05050006)the USTC Research Funds of the Double First-Class Initiative(Grant YD2060002032).
文摘The high activity and stability of intermetallic PtCo nanocatalysts toward oxygen reduction reaction make them a top candidate as low-Pt cathode catalysts in proton exchange membrane fuel cells(PEMFCs).However,forming intermetallic structures typically requires high-temperature annealing,posing a challenge for achieving well-size control and highly ordered structures.Here we report the design and synthesis of bimetallic co re@shell structured precursors for affording high-performance intermetallic PtCo catalysts.The fabrication of the core@shell precursor involves using a molecular ligand containing both sulfur and oxygen donors to selectively bind with Pt colloidal nanoparticles as the core and chelate Co ions as the shell.During high-temperature annealing,the ligand transforms into carbon coatings around alloy nanoparticles,preventing particle sintering;meanwhile,Co ions in the shell can easily diffuse into the Pt core,which helps to increase the thermodynamic driving force for forming intermetallic structures.These benefits enable us to obtain the catalyst with finely dispersed nanoparticles(~3.5 nm)and a high ordering degree of 72%.With 0.1 mgPt/cm^(2)cathode loading,the catalyst delivers superior performance and durability in PEMFCs,showing an initial mass activity of 0.56 A/mgPt,an initial power density of 1.05 W/cm^(2)at 0.67 V(H_(2)-air),and a voltage loss of 26 mV at 0.8 A/cm^(2)after the accelerated durability test.
基金supported by the National Natural Science Foundation of China(22008262)Natural Science Foundation of Shandong Province(ZR2020QB187).
文摘Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilization efficiency and durability by doping non-noble metals to form Pt-based alloy catalysts.Alloying Pt with Co has been recognized as one of the most effective approaches to achieve this goal.PtCo bimetal combination is one of the most promising candidates to synthesize highly efficient catalysts for oxygen reduction reaction(ORR)applications,owing to its relatively more suitable oxygen binding energy for four-electron transfer reactions.Recently,impressive strategies have been developed to fabricate more active and stable PtCo-based multimetallic alloys with tailorable size and morphology.This paper aims to summarize the most recent highlights on the study of the relationship between preparation strategies,morphologies,electroactivities of the PtCo-based catalyst at atomic level and further the relevant reaction mechanism.The challenges and opportunities on the further development of electrocatalysts for fuel cells are included to provide reference for the practical application.
基金supported by the National Natural Science Foundation of China(Nos.52372284,52275187)the Natural Science Foundation of Henan Province(Nos.242300420326,NSFRF240701,232300421135)+1 种基金Fundamental Research Funds for the Universities of Henan Province(No.NSFRF230433)National College Students'Innovation and Entrepreneurship Training Program(No.202310460063)。
文摘The methanol oxidation reaction is a critical half-reaction in direct methanol fuel cells(DMFCs),but its efficiency is limited by the low activity and poor stability of traditional electrocatalysts.This study reports the development of a high-performance PtCo/Mo_(2)CT_(x)catalyst for methanol oxidation in DMFCs.Synthesized by depositing PtCo alloy nanoparticles on Mo_(2)CT_(x)sheets prepared via cetyltrimethylammonium bromide-assisted etching of Mo2Ga2C,the PtCo/Mo_(2)CT_(x)catalyst achieved enhanced interlayer spacing and excellent dispersion of active sites.The optimized PtCo/Mo_(2)CT_(x)catalyst exhibited remarkable catalytic activity,reaching a mass activity of 2296 mA·mg_(Pt)^(-1)—6.5 times that of commercial Pt/C.Electrochemical studies confirmed the catalyst's low charge transfer resistance,high electrochemical surface area,and strong CO antipoisoning ability.Stability tests showed that the catalyst retained 62.26%activity after 1000 cycles.These improvements are attributed to the synergistic effects between Pt and Co,the conductive and layered structure of Mo_(2)CT_(x),making PtCo/Mo_(2)CT_(x)a promising,durable anode material for DMFCs in sustainable energy applications.
文摘Nanotwinned materials possess exceptional properties and represent a promising class of metastable materials.However,their controlled synthesis remains challenging.Here,we report the synthesis of twinned PtCo nanoparticles via a laser ablation approach,which promotes the formation of unique nanostructures.By optimizing laser parameters such as power and exposure time,we achieved a nanotwinning yield up to 61%,significantly higher than 12%in commercial PtCo.In proton-exchange membrane fuel cell tests,the nanotwinned PtCo catalyst demonstrated a mass activity of 0.56 A·mgPt^(-1) with 82.1%retention after accelerated stress testing.Notably,the voltage loss at 1 A·cm^(-2) was only 24.3 mV.Particle agglomeration and the reduction of stacking fault energy through alloying were identified as possible mechanisms for nanotwin formation.This work provides an efficient and rapid route for the controlled synthesis of nanotwinned particles,and the approach could potentially enable scalable production of high-performance catalysts.
基金National Natural Science Foundation of China (NSFC, 12174326, 11334003, 11674148,22350410375)Young Scientists Fund of the National Natural Science Foundation of China (52202306)+5 种基金Provincial Talent Plan (2023TB0012)Shenzhen Natural Science Foundation (GXWD20201231105722002-20200824163747001)Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2019ZT08L101)Program of Petro China Co.,Ltd.(2023ZZ1201)University Development Fund,Research Startup Fund (UDF01002976) from the Chinese University of Hong Kong(Shenzhen)Shenzhen Science and Technology Program(JCYJ20230807114302005)。
文摘The development of low-cost,highly active platinum(Pt)-based electrocatalysts for oxygen reduction reaction(ORR)is crucial for widespread applications of fuel cells.An effective approach lies in alloying Pt with non-noble transition metals to modulate the physicochemical state of the Pt surface.However,fundamental challenges remain in understanding the structure-performance relationship due to the complexity of composition,crystal type,and surface structure during the alloying process.In this study,we synthesized a series of PtCo bimetallic solid solutions with varying ratios using a liquid-phase synthesis method.By exploiting the characteristics of solid solutions,the resulting PtCo bimetallic alloy maintains the face-centered cubic crystal structure of pure platinum,minimizing the complexities introduced during alloying and facilitating mechanism analysis.Furthermore,under controlled alloy composition and crystal structure,we investigated the dependence of the electrocatalytic activity for the oxygen reduction reaction on the surface strain of the platinum catalyst.The S-PtCo-SNPs cathode designed accordingly endows both proton exchange membrane fuel cell(PEMFC)(2.08 W cm^(−2) at 4 A cm^(−2))and Zn-air battery(ZAB)(143.1 mW cm^(−2) at 214.5 mA cm^(−2))with outstanding performance.
