Utilizing Si, Fe and Mn concentrations within the end-member PACMANUS hydrothermal fluid, Si-Fe-Mn-H2O Pourbaix diagrams were constructed at 300℃and 25℃. ThePourbaix diagrams show that the main Si, Fe and Mn oxides ...Utilizing Si, Fe and Mn concentrations within the end-member PACMANUS hydrothermal fluid, Si-Fe-Mn-H2O Pourbaix diagrams were constructed at 300℃and 25℃. ThePourbaix diagrams show that the main Si, Fe and Mn oxides species precipitating from the hydrothermal fluid were SiO2, Fe（OH）3, Fe3（OH）8, Mn3O4, and Mn2O3at 25℃. During mixing of hydrothermal fluid with seawater, SiO2 precipitated earlier than Fe-Mn-oxyhydroxides because of the lower stability boundary. Then Fe（OH）2 precipitated first, followed by Fe3（OH）8 and Fe（OH）3, and last, small amounts of Mn3O4 and Mn2O3 precipitated. Fe（OH）3was readily de-posited in alkaline solution with little influence by Eh. There were many Si-Fe-Mn-concentric particles in the polished sections of the massive precipitates collected from PACMANUS. In the concentric nucleus and ellipsoid, Si oxides precipitated first before the hydrothermal fluid had mixed with seawater. In the concen-tric nucleus, after the precipitation of Si oxides, the increase of pH and Eh promoted the precipitation of Mn oxides around the Si oxides. In the large ellipsoid, the precipitation of Fe was divided into two periods. In the early period, increase of pH value of hydrothermal fluid produced by low-temperature convection and an input of a small volume of seawater promoted a small amount of Fe（OH）3 to precipitate in the Si-rich core. In the late period, after complete mixing with seawater and the resultant fluid was close to neutral or slightly alkaline in pH, Fe（OH）3was easily precipitated from the solution and distributed around the Si-rich core.展开更多
The design of cost-effective electrocatalysts is an open challenging for oxygen evolution reaction(OER)due to the“stable-oractive”dilemma.Zirconium dioxide(ZrO_(2)),a versatile and low-cost material that can be stab...The design of cost-effective electrocatalysts is an open challenging for oxygen evolution reaction(OER)due to the“stable-oractive”dilemma.Zirconium dioxide(ZrO_(2)),a versatile and low-cost material that can be stable under OER operating conditions,exhibits inherently poor OER activity from experimental observations.Herein,we doped a series of metal elements to regulate the ZrO_(2)catalytic activity in OER via spin-polarized density functional theory calculations with van der Waals interactions.Microkinetic modeling as a function of the OER activity descriptor(G_(O*)-G_(HO*))displays that 16 metal dopants enable to enhance OER activities over a thermodynamically stable ZrO_(2)surface,among which Fe and Rh(in the form of single-atom dopant)reach the volcano peak(i.e.the optimal activity of OER under the potential of interest),indicating excellent OER performance.Free energy diagram calculations,density of states,and ab initio molecular dynamics simulations further showed that Fe and Rh are the effective dopants for ZrO_(2),leading to low OER overpotential,high conductivity,and good stability.Considering cost-effectiveness,single-atom Fe doped ZrO_(2)emerged as the most promising catalyst for OER.This finding offers a valuable perspective and reference for experimental researchers to design cost-effective catalysts for the industrial-scale OER production.展开更多
Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we dem...Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we demonstrate that the surface of two-dimensional Co-based MOF is modified by decorating Ag quantum dots(QDs)simply through in-situ reduction of Ag+ions.Toward oxygen evolution reaction(OER),it reveals that the catalysis is mediated by the reversible redox of Co sites between Co^(3+) and Co^(4+) states coupling with transfer of OHions.The decoration of Ag QDs decreases the redox potential of Co sites,and thus effectively decreases the overpotential of OER.The TOFs of Co sites are increased by 77 times to reach 5.4 s^(-1) at an overpotential of 0.35 V.We attribute the activity enhancement to the tuning of the coupling process between Co sites and OHions during the redox of Co sites by Ag QDs decoration based on Pourbaix analysis.展开更多
A new viewpoint of computer program poubaix diagram was proposed on traditional φ pH diagrams. All equilibrium principle and activity term method were used to plot φ pH diagrams for M H 2O systems based on the therm...A new viewpoint of computer program poubaix diagram was proposed on traditional φ pH diagrams. All equilibrium principle and activity term method were used to plot φ pH diagrams for M H 2O systems based on the thermochemical database developed. And a new method——arithmetic geometric method is used to solve nonlinear equations group. The calculation procedure is proved to be efficient and convergent. The method seldom depends on artificial intervention and can extend to multi component all equilibrium φ pH diagrams such as M ligand H 2O system. [展开更多
基金The National Key Basic Research Program of China under contract Nos 2013CB429700the National Special Fund for the 12th Five Year Plan of COMRA under contract Nos DY125-12-R-02 and DY125-12-R-05+3 种基金the National Natural Science Foundation of China under contract Nos 41325021,40830849,40976027 and 41476044the Shandong Province Natural Science Foundation of China for Distinguished Young Scholars under contract Nos JQ200913the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11030302the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Utilizing Si, Fe and Mn concentrations within the end-member PACMANUS hydrothermal fluid, Si-Fe-Mn-H2O Pourbaix diagrams were constructed at 300℃and 25℃. ThePourbaix diagrams show that the main Si, Fe and Mn oxides species precipitating from the hydrothermal fluid were SiO2, Fe（OH）3, Fe3（OH）8, Mn3O4, and Mn2O3at 25℃. During mixing of hydrothermal fluid with seawater, SiO2 precipitated earlier than Fe-Mn-oxyhydroxides because of the lower stability boundary. Then Fe（OH）2 precipitated first, followed by Fe3（OH）8 and Fe（OH）3, and last, small amounts of Mn3O4 and Mn2O3 precipitated. Fe（OH）3was readily de-posited in alkaline solution with little influence by Eh. There were many Si-Fe-Mn-concentric particles in the polished sections of the massive precipitates collected from PACMANUS. In the concentric nucleus and ellipsoid, Si oxides precipitated first before the hydrothermal fluid had mixed with seawater. In the concen-tric nucleus, after the precipitation of Si oxides, the increase of pH and Eh promoted the precipitation of Mn oxides around the Si oxides. In the large ellipsoid, the precipitation of Fe was divided into two periods. In the early period, increase of pH value of hydrothermal fluid produced by low-temperature convection and an input of a small volume of seawater promoted a small amount of Fe（OH）3 to precipitate in the Si-rich core. In the late period, after complete mixing with seawater and the resultant fluid was close to neutral or slightly alkaline in pH, Fe（OH）3was easily precipitated from the solution and distributed around the Si-rich core.
基金the funding support from the Research Grants Council of the Hong Kong Special Administrative Region,China[Project No.CityU11308923]the Basic Research Project from Shenzhen Science and Technology Innovation Committee in Shenzhen,China(No.JCYJ20210324134012034)+5 种基金the Applied Research Grant of City University of Hong Kong(project No.of 9667247)Chow Sang Sang Group Research Fund of City University of Hong Kong(project No.9229123)the funding supported by the Seed Collaborative Research Fund Scheme of State Key Laboratory of Marine Pollution which receives regular research funding from Innovation and Technology Commission(ITC)of the Hong Kong SAR Governmentthe JSPS KAKENHI(No.JP23K13703 and JP23KF0102)the high-level science and technology talents project of Lvliang City(No.2022RC07)foundation of Shanxi supercomputing center of China(No.11sxsc202301).
文摘The design of cost-effective electrocatalysts is an open challenging for oxygen evolution reaction(OER)due to the“stable-oractive”dilemma.Zirconium dioxide(ZrO_(2)),a versatile and low-cost material that can be stable under OER operating conditions,exhibits inherently poor OER activity from experimental observations.Herein,we doped a series of metal elements to regulate the ZrO_(2)catalytic activity in OER via spin-polarized density functional theory calculations with van der Waals interactions.Microkinetic modeling as a function of the OER activity descriptor(G_(O*)-G_(HO*))displays that 16 metal dopants enable to enhance OER activities over a thermodynamically stable ZrO_(2)surface,among which Fe and Rh(in the form of single-atom dopant)reach the volcano peak(i.e.the optimal activity of OER under the potential of interest),indicating excellent OER performance.Free energy diagram calculations,density of states,and ab initio molecular dynamics simulations further showed that Fe and Rh are the effective dopants for ZrO_(2),leading to low OER overpotential,high conductivity,and good stability.Considering cost-effectiveness,single-atom Fe doped ZrO_(2)emerged as the most promising catalyst for OER.This finding offers a valuable perspective and reference for experimental researchers to design cost-effective catalysts for the industrial-scale OER production.
基金gratefully acknowledge the financial support from the National Natural Science Foundation of China(51802265,22002119)the Fundamental Research Funds for the Central Universities of China+2 种基金the Initiative Postdocs Supporting Program(BX20190281)the General Program,Science and Technology Program of Taicang,China(TC2020JC01)the National Natural Science Foundation of Jiangsu,China(BK20200261)。
文摘Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we demonstrate that the surface of two-dimensional Co-based MOF is modified by decorating Ag quantum dots(QDs)simply through in-situ reduction of Ag+ions.Toward oxygen evolution reaction(OER),it reveals that the catalysis is mediated by the reversible redox of Co sites between Co^(3+) and Co^(4+) states coupling with transfer of OHions.The decoration of Ag QDs decreases the redox potential of Co sites,and thus effectively decreases the overpotential of OER.The TOFs of Co sites are increased by 77 times to reach 5.4 s^(-1) at an overpotential of 0.35 V.We attribute the activity enhancement to the tuning of the coupling process between Co sites and OHions during the redox of Co sites by Ag QDs decoration based on Pourbaix analysis.
文摘A new viewpoint of computer program poubaix diagram was proposed on traditional φ pH diagrams. All equilibrium principle and activity term method were used to plot φ pH diagrams for M H 2O systems based on the thermochemical database developed. And a new method——arithmetic geometric method is used to solve nonlinear equations group. The calculation procedure is proved to be efficient and convergent. The method seldom depends on artificial intervention and can extend to multi component all equilibrium φ pH diagrams such as M ligand H 2O system. [
