High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion te...High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.展开更多
The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice co...The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice contraction and microcrystallization was synthesized via a simple one-step method using sodium gluconate.The lattice contraction is attributed to the interaction of carbon in sodium gluconate and iron in NiFe LDH.The NiFe LDH with optimized microcrystallization and lattice contraction shows a low overpotential of 217 mV at a current density of 10 mA cm^(−2) and excellent durability of 20 h at a high current density of 100 mA cm^(−2).The results revealed that a contractive metal–oxygen bond could boost the intrinsic activity of active sites and the microcrystallization promotes an increase in the number of active sites in terms of unit area.The chemical environment of oxygen elemental characterization and resistance at different chronopotentiometry times confirm that the lattice oxygen element is indeed involved in the process of OER,supporting the lattice-oxygen-mediated mechanism of NiFe LDH.Density functional theory calculations reveal that contractive metal–oxygen bonds induced a reduction of the adsorption energy barrier of intermediate products,thus improving the intrinsic catalytic activity.The special characteristics of microcrystallization and lattice contraction of NiFe LDH provide a strategy to improve both the number and the intrinsic activity of active sites in a versatile manner.展开更多
The oxygen evolution reaction(OER)represents an anodic reaction for a variety of sustainable energy conversion and storage technologies,such as hydrogen production,CO_(2) reduction,etc.To realize the large-scale imple...The oxygen evolution reaction(OER)represents an anodic reaction for a variety of sustainable energy conversion and storage technologies,such as hydrogen production,CO_(2) reduction,etc.To realize the large-scale implementation of these technologies,the sluggish kinetics of the OER resulting from multistep proton/electron transfer and occurring at the gas–liquid–solid triple-phase boundary needs to be accelerated.Manganese oxide-based(MnO_(x))materials,especially MnO_(2),have become promising nonprecious metal electrocatalysts for the OER under acidic conditions due to the good trade-off between catalytic activity and stability.This paper reviews the recent progress of MnO_(2)-based materials to catalyze the OER through either the traditional adsorbent formation mechanism(AEM)or the emerging latticeoxygen-mediated mechanism(LOM).Pure manganese dioxide OER catalysts with different crystalline structures and morphologies are summarized,while MnO2-based composite structures are also discussed,and the application of MnO_(2)-based catalysts in PEMWEs is summarized.Critical challenges and future research directions are presented to hopefully help future research.展开更多
基金the staff at Beamline (BL08U1-A and BL11B)of the Shanghai Synchrotron Radiation Facility (SSRF)the support from the National Key Research&Development Program of China (2022YFB3803700)+2 种基金the National Natural Science Foundation of China (52171186)the support through the Overseas Outstanding Youth Fund and Shanghai Pujiang Talent Project (21PJ1408500)the financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘High efficiency,cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems.The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies.Herein,we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction(OER)for alkaline electrolysis,which yields current density of 10 mA cm^(-2)at an overpotential of 215 mV in 0.1 M KOH electrolyte.The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity.Raman spectra revealed that the catalyst underwent structure reconstruction during OER,evolving into oxyhydroxide,which was the active site proceeding OER in alkaline electrolyte.In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst.This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability.These findings provide promising strategies for the rational design of nonnoble metal OER catalysts.
基金National Natural Science Foundation of China,Grant/Award Numbers:51874357,51872333,U20A20123。
文摘The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice contraction and microcrystallization was synthesized via a simple one-step method using sodium gluconate.The lattice contraction is attributed to the interaction of carbon in sodium gluconate and iron in NiFe LDH.The NiFe LDH with optimized microcrystallization and lattice contraction shows a low overpotential of 217 mV at a current density of 10 mA cm^(−2) and excellent durability of 20 h at a high current density of 100 mA cm^(−2).The results revealed that a contractive metal–oxygen bond could boost the intrinsic activity of active sites and the microcrystallization promotes an increase in the number of active sites in terms of unit area.The chemical environment of oxygen elemental characterization and resistance at different chronopotentiometry times confirm that the lattice oxygen element is indeed involved in the process of OER,supporting the lattice-oxygen-mediated mechanism of NiFe LDH.Density functional theory calculations reveal that contractive metal–oxygen bonds induced a reduction of the adsorption energy barrier of intermediate products,thus improving the intrinsic catalytic activity.The special characteristics of microcrystallization and lattice contraction of NiFe LDH provide a strategy to improve both the number and the intrinsic activity of active sites in a versatile manner.
基金This work was supported by the Hainan Provincial Natural Science Foundation of China(222MS006,221RC1017,522QN281222RC554,211RC018,222RC548,521RC495)the Hainan Province Science and Technology Special Fund(ZDYF2021GXJS207,ZDYF2020037,2020207)+1 种基金the National Natural Science Foundation of China(22109034,22109035,52164028,62105083)the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20082,20083,20084,21065,21124,21125).
文摘The oxygen evolution reaction(OER)represents an anodic reaction for a variety of sustainable energy conversion and storage technologies,such as hydrogen production,CO_(2) reduction,etc.To realize the large-scale implementation of these technologies,the sluggish kinetics of the OER resulting from multistep proton/electron transfer and occurring at the gas–liquid–solid triple-phase boundary needs to be accelerated.Manganese oxide-based(MnO_(x))materials,especially MnO_(2),have become promising nonprecious metal electrocatalysts for the OER under acidic conditions due to the good trade-off between catalytic activity and stability.This paper reviews the recent progress of MnO_(2)-based materials to catalyze the OER through either the traditional adsorbent formation mechanism(AEM)or the emerging latticeoxygen-mediated mechanism(LOM).Pure manganese dioxide OER catalysts with different crystalline structures and morphologies are summarized,while MnO2-based composite structures are also discussed,and the application of MnO_(2)-based catalysts in PEMWEs is summarized.Critical challenges and future research directions are presented to hopefully help future research.
