The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, iono...The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, ionomer, and Pt nanoparticles, all immersed together and sprayed with a micron-level thickness of CLs. They have a performance trade-off where increasing the Pt loading leads to higher performance of abundant triple-phase boundary areas but increases the electrode cost. Major challenges must be overcome before realizing its wide commercialization. Literature research revealed that it is impossible to achieve performance and durability targets with only high-performance catalysts, so the controllable design of CLs architecture in MEAs for PEMFCs must now be the top priority to meet industry goals. From this perspective, a 3D ordered electrode circumvents this issue with a support-free architecture and ultrathin thickness while reducing noble metal Pt loadings. Herein, we discuss the motivation in-depth and summarize the necessary CLs structural features for designing ultralow Pt loading electrodes. Critical issues that remain in progress for 3D ordered CLs must be studied and characterized. Furthermore, approaches for 3D ordered CLs architecture electrode development, involving material design, structure optimization, preparation technology, and characterization techniques, are summarized and are expected to be next-generation CLs for PEMFCs. Finally, the review concludes with perspectives on possible research directions of CL architecture to address the significant challenges in the future.展开更多
Constructing own oxygen vacancies in the photocatalysts is a very promising method to improve their photocatalytic CO_(2)reduction activity.However,some catalysts have excellent stabilities,making it difficult for the...Constructing own oxygen vacancies in the photocatalysts is a very promising method to improve their photocatalytic CO_(2)reduction activity.However,some catalysts have excellent stabilities,making it difficult for them to construct their own oxygen vacancies.To simplify the above difficulty of stable photocatalysts,constructing extrinsic oxygen vacancies on their surface as a novel idea is proposed.Here,a stable TiO_(2)nanosheet is chosen as a research object,we uniformly deposited BiOCl quantum dots on their surface via a simple adsorption-deposition method.It is found that BiOCl quantum dots are able to simultaneously self-transform into defective BiOCl with many oxygen vacancies when the photocatalyst is performed photocatalytic CO_(2)reduction.These extrinsic oxygen vacancies can act as“CO_(2)and photo-generated electrons reservoirs”to improve CO_(2)capture and accelerate the separation of photogenerated electrons and holes.For the above reasons,the modified TiO_(2)showed obvious enhancement of photocatalytic CO_(2)reduction compared to pristine TiO_(2)and BiOCl.This work may open a new avenue to broaden the use of oxygen vacancies in the process of photocatalytic CO_(2)reduction.展开更多
The concentration of atmospheric CO_(2)has exceeded 400 ppm,surpassing its natural variability and raising concerns about uncontrollable shifts in the carbon cycle,leading to significant climate and environmental impa...The concentration of atmospheric CO_(2)has exceeded 400 ppm,surpassing its natural variability and raising concerns about uncontrollable shifts in the carbon cycle,leading to significant climate and environmental impacts.A promising method to balance carbon levels and mitigate atmospheric CO_(2)rise is through photocatalytic CO_(2)reduction.Titanium dioxide(TiO_(2)),renowned for its affordability,stability,availability,and eco-friendliness,stands out as an exemplary catalyst in photocatalytic CO_(2)reduction.Various strategies have been proposed to modify TiO_(2)for photocatalytic CO_(2)reduction and improve catalytic activity and product selectivity.However,few studies have systematically summarized these strategies and analyzed their advantages,disadvantages,and current progress.Here,we comprehensively review recent advancements in TiO_(2)engineering,focusing on crystal engineering,interface design,and reactive site construction to enhance photocatalytic efficiency and product selectivity.We discuss how modifications in TiO_(2)'s optical characteristics,carrier migration,and active site design have led to varied and selective CO_(2)reduction products.These enhancements are thoroughly analyzed through experimental data and theoretical calculations.Additionally,we identify current challenges and suggest future research directions,emphasizing the role of TiO_(2)-based materials in understanding photocatalytic CO_(2)reduction mechanisms and in designing effective catalysts.This review is expected to contribute to the global pursuit of carbon neutrality by providing foundational insights into the mechanisms of photocatalytic CO_(2)reduction with TiO_(2)-based materials and guiding the development of efficient photocatalysts.展开更多
Polyoxometalates(POMs),as a class of multinuclear clusters,are polymerized of oxygen and early high-valent transition metals(e.g.,Mo,W,V and Nb).Based on the geometry of heteroatoms and the ratio of heteroatoms to coo...Polyoxometalates(POMs),as a class of multinuclear clusters,are polymerized of oxygen and early high-valent transition metals(e.g.,Mo,W,V and Nb).Based on the geometry of heteroatoms and the ratio of heteroatoms to coordination atoms,POMs can be classified into six classical configurations including Keggin-type,Dawson-type,Anderson-type,Waugh-type,Silverton-type,and Lindqvist-type.They exhibit the diverse structures and versatile properties,which enrich their applications in catalysis,medicine,electrochemistry,magnetism,and so on.The chemistry of POMs is an important branch of inorganic chemistry with a history of more than 200 years.It intersects with physical chemistry,analytical chemistry,structural chemistry,biochemistry,environmental chemistry,material chemistry and many other fields.Modern chemistry of POMs has developed from single POMs synthesis to controllable molecular design synthesis,from simple POMs monomer to high-dimensional,high-core and other novel structure clusters constructed with POMs as building units.Especially,POMs are considered as electron stores due to their strong ability to bear and release electrons,indicating they have redox properties.Therefore,POMs have received increasing attentions as redox heterogeneous catalysts.To resolve the problem of the high solubility of POMs,the design synthesis and performance research of functional complexes with POMs as inorganic ligands or non-coordination templates have become one of hot spots.The encapsulation of POMs into the crystalline architecture results in multifunctional hybrid materials,which combine the merits of POMs and the organic frameworks to achieve specific properties.With the increase of consciousness for environmental protection,green oxidants such as hydrogen peroxide and oxygen are utilized as main oxidants for the oxidation.The combination of POMs-based materials with environment friendly oxidants can efficiently catalyze various oxidation reactions,such as epoxidation of olefin,oxidation of sulfurcontaining compounds,oxidation of alcohols,oxidation of alkanes and so on.In this paper,an overview of recent advances of POMs in catalytic oxidation was presented.展开更多
Modulating the surface coordination environment of Pt based nanocrystals at the atomic level is of great importance to obtain good electrocatalytic performance.Given the fundamental understandings of surface structure...Modulating the surface coordination environment of Pt based nanocrystals at the atomic level is of great importance to obtain good electrocatalytic performance.Given the fundamental understandings of surface structure degeneration of Pt based nanocrystals,introducing a weak electronegative element to the surface of Pt-based catalysts is beneficial for suppressing surface passivation and improving hydrogen evolution reaction performance of Pt.Density functional theory results reveal that the energy barrier of water dissociation process can be greatly reduced by using Se element as the surface modifier to replace the O.This hypothesis is further validated by experiments that ultralong Pt_(85)Mo_(15)-Se nanowires were fabricated to suppress the excessive passivation behavior of transition metals of Pt based alloy.The Pt_(85)Mo_(15)-Se nanowires exhibit higher activity with 4.98 times the specific activity and 4.87 times the mass activity of commercial Pt/C,as well as a better stability towards alkaline hydrogen evolution reaction.The deep exploration of X-ray photoelectron spectroscopy and theoretical calculations disclose that Se element could maintain the electron-rich state around the electronic orbit of Pt.This study provides a new insight to advance the fundamental understanding on electrocatalytic materials,which exhibits a promising approach to protect the surface chemical environment of Pt based nanocrystals.展开更多
基金funded by the Natural Science Foundation of Shandong Province, China (ZR2023MB049)the China Postdoctoral Science Foundation (2020M670483)the Science Foundation of Weifang University (2023BS11)。
文摘The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, ionomer, and Pt nanoparticles, all immersed together and sprayed with a micron-level thickness of CLs. They have a performance trade-off where increasing the Pt loading leads to higher performance of abundant triple-phase boundary areas but increases the electrode cost. Major challenges must be overcome before realizing its wide commercialization. Literature research revealed that it is impossible to achieve performance and durability targets with only high-performance catalysts, so the controllable design of CLs architecture in MEAs for PEMFCs must now be the top priority to meet industry goals. From this perspective, a 3D ordered electrode circumvents this issue with a support-free architecture and ultrathin thickness while reducing noble metal Pt loadings. Herein, we discuss the motivation in-depth and summarize the necessary CLs structural features for designing ultralow Pt loading electrodes. Critical issues that remain in progress for 3D ordered CLs must be studied and characterized. Furthermore, approaches for 3D ordered CLs architecture electrode development, involving material design, structure optimization, preparation technology, and characterization techniques, are summarized and are expected to be next-generation CLs for PEMFCs. Finally, the review concludes with perspectives on possible research directions of CL architecture to address the significant challenges in the future.
基金financially supported by the National Natural Science Foundation of China(No.21637005)the China Postdoctoral Science Foundation(No.2020M670483)。
文摘Constructing own oxygen vacancies in the photocatalysts is a very promising method to improve their photocatalytic CO_(2)reduction activity.However,some catalysts have excellent stabilities,making it difficult for them to construct their own oxygen vacancies.To simplify the above difficulty of stable photocatalysts,constructing extrinsic oxygen vacancies on their surface as a novel idea is proposed.Here,a stable TiO_(2)nanosheet is chosen as a research object,we uniformly deposited BiOCl quantum dots on their surface via a simple adsorption-deposition method.It is found that BiOCl quantum dots are able to simultaneously self-transform into defective BiOCl with many oxygen vacancies when the photocatalyst is performed photocatalytic CO_(2)reduction.These extrinsic oxygen vacancies can act as“CO_(2)and photo-generated electrons reservoirs”to improve CO_(2)capture and accelerate the separation of photogenerated electrons and holes.For the above reasons,the modified TiO_(2)showed obvious enhancement of photocatalytic CO_(2)reduction compared to pristine TiO_(2)and BiOCl.This work may open a new avenue to broaden the use of oxygen vacancies in the process of photocatalytic CO_(2)reduction.
基金financially supported by the National Natural Science Foundation of China(22005123,22188102)the Natural Science Foundation of Shandong Province,China(ZR2023MB049)+1 种基金China Postdoctoral Science Foundation(2020M670483)the Key Project of Natural Science Foundation of Tianjin City(Contract No.22JCZDJC00510).
文摘The concentration of atmospheric CO_(2)has exceeded 400 ppm,surpassing its natural variability and raising concerns about uncontrollable shifts in the carbon cycle,leading to significant climate and environmental impacts.A promising method to balance carbon levels and mitigate atmospheric CO_(2)rise is through photocatalytic CO_(2)reduction.Titanium dioxide(TiO_(2)),renowned for its affordability,stability,availability,and eco-friendliness,stands out as an exemplary catalyst in photocatalytic CO_(2)reduction.Various strategies have been proposed to modify TiO_(2)for photocatalytic CO_(2)reduction and improve catalytic activity and product selectivity.However,few studies have systematically summarized these strategies and analyzed their advantages,disadvantages,and current progress.Here,we comprehensively review recent advancements in TiO_(2)engineering,focusing on crystal engineering,interface design,and reactive site construction to enhance photocatalytic efficiency and product selectivity.We discuss how modifications in TiO_(2)'s optical characteristics,carrier migration,and active site design have led to varied and selective CO_(2)reduction products.These enhancements are thoroughly analyzed through experimental data and theoretical calculations.Additionally,we identify current challenges and suggest future research directions,emphasizing the role of TiO_(2)-based materials in understanding photocatalytic CO_(2)reduction mechanisms and in designing effective catalysts.This review is expected to contribute to the global pursuit of carbon neutrality by providing foundational insights into the mechanisms of photocatalytic CO_(2)reduction with TiO_(2)-based materials and guiding the development of efficient photocatalysts.
基金supported by the Doctoral Scientific Research Foundation of Weifang University(2023BS13)the Project of Weifang Science and Technology Development Program(2022GX 020 and 2022GX021)+1 种基金the National Natural Science Foundation of China(22001032)the Doctoral Scientific Research Foundation of Weifang Vocational College(Preparation and electrochemical properties of high performance polyoxometallatebased lithium-ion battery anode materials)
文摘Polyoxometalates(POMs),as a class of multinuclear clusters,are polymerized of oxygen and early high-valent transition metals(e.g.,Mo,W,V and Nb).Based on the geometry of heteroatoms and the ratio of heteroatoms to coordination atoms,POMs can be classified into six classical configurations including Keggin-type,Dawson-type,Anderson-type,Waugh-type,Silverton-type,and Lindqvist-type.They exhibit the diverse structures and versatile properties,which enrich their applications in catalysis,medicine,electrochemistry,magnetism,and so on.The chemistry of POMs is an important branch of inorganic chemistry with a history of more than 200 years.It intersects with physical chemistry,analytical chemistry,structural chemistry,biochemistry,environmental chemistry,material chemistry and many other fields.Modern chemistry of POMs has developed from single POMs synthesis to controllable molecular design synthesis,from simple POMs monomer to high-dimensional,high-core and other novel structure clusters constructed with POMs as building units.Especially,POMs are considered as electron stores due to their strong ability to bear and release electrons,indicating they have redox properties.Therefore,POMs have received increasing attentions as redox heterogeneous catalysts.To resolve the problem of the high solubility of POMs,the design synthesis and performance research of functional complexes with POMs as inorganic ligands or non-coordination templates have become one of hot spots.The encapsulation of POMs into the crystalline architecture results in multifunctional hybrid materials,which combine the merits of POMs and the organic frameworks to achieve specific properties.With the increase of consciousness for environmental protection,green oxidants such as hydrogen peroxide and oxygen are utilized as main oxidants for the oxidation.The combination of POMs-based materials with environment friendly oxidants can efficiently catalyze various oxidation reactions,such as epoxidation of olefin,oxidation of sulfurcontaining compounds,oxidation of alcohols,oxidation of alkanes and so on.In this paper,an overview of recent advances of POMs in catalytic oxidation was presented.
基金gratefully acknowledge the Science Foundation of Weifang University(No.2020BS16)the Natural Science Foundation of Shandong Province(No.ZR2019BEM017 and ZR2017MB056)the financial support of the National Natural Science Foundation of China(No.21802104).
文摘Modulating the surface coordination environment of Pt based nanocrystals at the atomic level is of great importance to obtain good electrocatalytic performance.Given the fundamental understandings of surface structure degeneration of Pt based nanocrystals,introducing a weak electronegative element to the surface of Pt-based catalysts is beneficial for suppressing surface passivation and improving hydrogen evolution reaction performance of Pt.Density functional theory results reveal that the energy barrier of water dissociation process can be greatly reduced by using Se element as the surface modifier to replace the O.This hypothesis is further validated by experiments that ultralong Pt_(85)Mo_(15)-Se nanowires were fabricated to suppress the excessive passivation behavior of transition metals of Pt based alloy.The Pt_(85)Mo_(15)-Se nanowires exhibit higher activity with 4.98 times the specific activity and 4.87 times the mass activity of commercial Pt/C,as well as a better stability towards alkaline hydrogen evolution reaction.The deep exploration of X-ray photoelectron spectroscopy and theoretical calculations disclose that Se element could maintain the electron-rich state around the electronic orbit of Pt.This study provides a new insight to advance the fundamental understanding on electrocatalytic materials,which exhibits a promising approach to protect the surface chemical environment of Pt based nanocrystals.
