Shuxin Ouyang - Cochemist

Synergistic Activity of Co and Fe in Amorphous Cox–Fe–B Catalyst for Efficient Oxygen Evolution Reaction

Co-reporter:Huayu Chen, Shuxin Ouyang, Ming Zhao, Yunxiang Li, and Jinhua Ye

ACS Applied Materials & Interfaces November 22, 2017 Volume 9(Issue 46) pp:40333-40333

Publication Date(Web):November 7, 2017

DOI:10.1021/acsami.7b13939

Water splitting has been greatly limited by the sluggish kinetics of the oxygen evolution reaction (OER). High-oxidation-state metal species are required as the favorable active sites in OER. Here, amorphous Cox–Fe–B (x is the molar ratio of Co/Fe), Co–B, and Fe–B compounds were successfully synthesized as the oxygen evolution electrocatalysts. The calculation of turnover frequency (TOF) indicates that both the Co and Fe sites are active for OER. Cyclic voltammetry, X-ray photoelectron spectroscopy, and long-term stability curves were used to demonstrate that Fe can stabilize Co in a higher oxidation level and meanwhile promote the generation of OOH-like species (the key intermediates for OER). The reduced impedance for Co2–Fe–B (compared with that for Fe–B and Co–B) obtained from the electrochemical impedance spectra confirms the enhanced conductivity for the Co2–Fe–B. This optimal sample on Cu substrate shows a low overpotential of 0.298 V at the current density of 10 mA cm–2 with a decreased overpotential of 42 mV compared to that of Co–B. The Co2–Fe–B catalyst also exhibits a small Tafel slope of 62.6 mV/dec and good stability. The enhanced performance could be attributed to the synergistic effect of the increased population of high-oxidation-state metal–OOH species and the promoted conductivity of the catalyst. A solar-to-hydrogen energy conversion efficiency of 4.2% and a Faradaic efficiency of 97.2% can be achieved by connecting the HER and as-prepared OER electrodes to a crystalline silicon solar cell.Keywords: 3d metal; boride; electrocatalyst; oxygen evolution reaction; photovoltaic water splitting;

Constructing Solid–Gas-Interfacial Fenton Reaction over Alkalinized-C3N4 Photocatalyst To Achieve Apparent Quantum Yield of 49% at 420 nm

Co-reporter:Yunxiang Li, Shuxin Ouyang, Hua Xu, Xin Wang, Yingpu Bi, Yuanfang Zhang, and Jinhua Ye

Journal of the American Chemical Society 2016 Volume 138(Issue 40) pp:13289-13297

Publication Date(Web):September 19, 2016

DOI:10.1021/jacs.6b07272

Efficient generation of active oxygen-related radicals plays an essential role in boosting advanced oxidation process. To promote photocatalytic oxidation for gaseous pollutant over g-C3N4, a solid–gas interfacial Fenton reaction is coupled into alkalinized g-C3N4-based photocatalyst to effectively convert photocatalytic generation of H2O2 into oxygen-related radicals. This system includes light energy as power, alkalinized g-C3N4-based photocatalyst as an in situ and robust H2O2 generator, and surface-decorated Fe3+ as a trigger of H2O2 conversion, which attains highly efficient and universal activity for photodegradation of volatile organic compounds (VOCs). Taking the photooxidation of isopropanol as model reaction, this system achieves a photoactivity of 2–3 orders of magnitude higher than that of pristine g-C3N4, which corresponds to a high apparent quantum yield of 49% at around 420 nm. In-situ electron spin resonance (ESR) spectroscopy and sacrificial-reagent incorporated photocatalytic characterizations indicate that the notable photoactivity promotion could be ascribed to the collaboration between photocarriers (electrons and holes) and Fenton process to produce abundant and reactive oxygen-related radicals. The strategy of coupling solid–gas interfacial Fenton process into semiconductor-based photocatalysis provides a facile and promising solution to the remediation of air pollution via solar energy.

In situ surface alkalinized g-C3N4 toward enhancement of photocatalytic H2 evolution under visible-light irradiation

Co-reporter:Yunxiang Li, Hua Xu, Shuxin Ouyang, Da Lu, Xin Wang, Defa Wang and Jinhua Ye

Journal of Materials Chemistry A 2016 vol. 4(Issue 8) pp:2943-2950

Publication Date(Web):05 Aug 2015

DOI:10.1039/C5TA05128B

Surface-alkalinization over g-C3N4 was realized by an in situ synthesis approach of introducing KCl and NH4Cl during the polymerization of melamine. The characterization of the Fourier transform-infrared spectrum, X-ray photoelectron spectrum, and electron spin resonance spectrum over the sample synthesized in the presence of KCl/NH4Cl and other reference samples indicated that the K ions played an essential role in breaking the periodic chemical structure of g-C3N4 and meanwhile the trace amount of H2O in melamine could supply OH ions to graft hydroxyl groups. The NH4Cl mainly contributed to exfoliation of layered g-C3N4 particles and pushing negative shift of the conduction-band level based on the measurements of the BET surface area and valence-band X-ray photoelectron spectrum. An optimal sample, g–C3N4–KCl/0.1 g NH4Cl (CN–KCl/0.1 g NH4Cl), achieved a more than 14-fold enhancement in photocatalytic H2 evolution under visible-light irradiation compared with the pristine g-C3N4. The enhanced photocatalytic efficiency could be attributed to the fact that the surface hydroxyl groups and the more negative conduction-band level can promote the separation of photocarriers and offer a stronger potential for water reduction, respectively.

Designing Au Surface-Modified Nanoporous-Single-Crystalline SrTiO3 to Optimize Diffusion of Surface Plasmon Resonance-Induce Photoelectron toward Enhanced Visible-Light Photoactivity

Co-reporter:Da Lu, Shuxin Ouyang, Hua Xu, Dewang Li, Xueliang Zhang, Yunxiang Li, and Jinhua Ye

ACS Applied Materials & Interfaces 2016 Volume 8(Issue 14) pp:9506

Publication Date(Web):March 23, 2016

DOI:10.1021/acsami.6b00889

Nanoporous single-crystalline SrTiO3 is fabricated at a low temperature of 60 °C via a novel approach of sol–gel alkali-dissolution-exothermal reaction. The plasmon-active metal Au is loaded on the nanoporous single-crystalline SrTiO3 material to construct a new kind of plasmonic photocatalyst. Due to the single-crystalline nature and the space confinement effect of pores for Au growing, not only the promoted diffusion efficiency of surface plasmon resonance (SPR)-induce photoelectron is achieved, but also the diffusion region are well optimized via changing the loading amount of Au. Therefore, an optimal sample with 4.8 wt % Au loading exhibits a more than 40-fold photoactivity enhancement under visible-light irradiation compared to the common nanosized SrTiO3 (a commercially available sample) loaded with 5.3 wt % Au which was prepared under the same condition. Furthermore, combining the special nanostructure of Au surface-modified nanoporous-single-crystalline SrTiO3 with photocatalytic properties, estimation of the diffusion mean free path of SPR-induce photoelectron can be achieved. This study proposes an alternative approach to enhance the photoactivity of plasmonic photocatalyst via fine designing the semiconductor substrate.Keywords: Au; isopropyl alcohol photodegradation; nanoporous single-crystalline material; plasmonic photocatalysis; SrTiO3

Synergistic effect of Au and Rh on SrTiO3 in significantly promoting visible-light-driven syngas production from CO2 and H2O

Co-reporter:Dewang Li, Shuxin Ouyang, Hua Xu, Da Lu, Ming Zhao, Xueliang Zhang and Jinhua Ye

Chemical Communications 2016 vol. 52(Issue 35) pp:5989-5992

Publication Date(Web):31 Mar 2016

DOI:10.1039/C6CC00836D

A novel photocatalyst constructed by Rh, Au, and SrTiO3 was developed to realize syngas photosynthesis from low-cost CO2 and H2O feedstock under visible-light irradiation. The synergistic effect of Rh and Au on SrTiO3 contributed to a 22- and 153-fold photoactivity magnification for syngas yield in contrast to Au@SrTiO3 and Rh@SrTiO3 samples, respectively.

Modulation of sulfur partial pressure in sulfurization to significantly improve the photoelectrochemical performance over the Cu2ZnSnS4 photocathode

Co-reporter:Yuanfang Zhang, Shuxin Ouyang, Qing Yu, Peng Li and Jinhua Ye

Chemical Communications 2015 vol. 51(Issue 74) pp:14057-14059

Publication Date(Web):28 Jul 2015

DOI:10.1039/C5CC04812E

Cu2ZnSnS4 photocathodes with excellent photoelectrochemical properties were fabricated via a facile method of adjusting the sulfur partial pressure in a semi-closed system, which achieved a maximum photocurrent-density of 1.8 mA cm−2 under irradiation of a solar simulator which is 9-fold larger than that synthesized in an open system.

An Ag3PO4/nitridized Sr2Nb2O7 composite photocatalyst with adjustable band structures for efficient elimination of gaseous organic pollutants under visible light irradiation

Co-reporter:Jianjun Guo, Han Zhou, Shuxin Ouyang, Tetsuya Kako and Jinhua Ye

Nanoscale 2014 vol. 6(Issue 13) pp:7303-7311

Publication Date(Web):21 Mar 2014

DOI:10.1039/C4NR00537F

A new Ag3PO4/nitridized Sr2Nb2O7 (N: 0–6.18 wt%) heterojunction was designed to eliminate gaseous pollutants under visible light irradiation. The phase compositions, optical properties, and morphologies of the heterojunction photocatalysts were systematically investigated via powder X-ray diffraction, UV-visible absorption spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Calculations of the electronic structure indicated that the top of the valance band of Sr2Nb2O7 could be raised by nitrogen doping. Therefore, the electronic structure of the Ag3PO4/nitridized Sr2Nb2O7 composite photocatalysts could be continually changed by controlling the amount of nitrogen in nitridized Sr2Nb2O7. Photocatalytic degradation of isopropyl alcohol (IPA) was carried out to test the photocatalytic activity of the heterojunction. The highest activity (CO2 evolution rate, 10.32 ppm h−1) was observed over the Ag3PO4/nitridized Sr2Nb2O7 heterojunction prepared by nitridation of Sr2Nb2O7 (SNO) at 1023 K. The CO2 evolution rate over the heterojunction was about 40 times higher than that over pure Ag3PO4 (CO2 evolution rate, 0.26 ppm h−1) under visible light irradiation. An investigation of the energy-band structure via valence band X-ray photoelectron spectroscopy indicated that the conduction band (CB) and valence band (VB) of Ag3PO4 are both more positive than those of nitridized Sr2Nb2O7, which facilitates the separation and transfer of photogenerated electrons and holes between the two photocatalysts. By continually adjusting the electronic structures, an optimal band gap for the nitridized Sr2Nb2O7 of 2.15 eV was obtained, and the potential of the valance band was +1.88 eV.

Bifunctional-Nanotemplate Assisted Synthesis of Nanoporous SrTiO3 Photocatalysts Toward Efficient Degradation of Organic Pollutant

Co-reporter:Shuxin Ouyang, Peng Li, Hua Xu, Hua Tong, Lequan Liu, and Jinhua Ye

ACS Applied Materials & Interfaces 2014 Volume 6(Issue 24) pp:22726

Publication Date(Web):November 21, 2014

DOI:10.1021/am506877b

Nanoporous SrTiO3 photocatalysts were fabricated via a novel technique, the nanotemplate assisted sol–gel hydrothermal reaction. In the alkaline-environment hydrothermal reaction, the SiO2 nanotemplate not only served as pore generator but also worked on adjusting the local reaction environment around the SrTiO3 nanocrystals. This contributed to a continuous modulation between the surface area and the crystallinity of the photocatalyst. The photocatalytic activities of the nanoporous SrTiO3 samples were evaluated by the degradation of gaseous isopropyl alcohol (IPA). Due to an optimal equilibrium between surface area and crystallinity, a SrTiO3 sample synthesized via adding 40% template (STO-SiO2-40%) showed the highest activity, which achieves 40 and 8 times of enhancement of CO2 evolution in comparison with the sample prepared without template and a commercial nano-SrTiO3, respectively. The photodegradation mechanism of IPA over this sample was also investigated in detail. This synthetic technique is also available to prepare the other nanoporous titanates, such as doped SrTiO3 samples and alkali-metal titanates.Keywords: crystallinity; nanoporous material; nanotemplate; organic pollutant photodegradation; photocatalysis; surface area

Photothermal Conversion of CO2 into CH4 with H2 over GroupVIII Nanocatalysts: An Alternative Approach for Solar Fuel Production

Co-reporter:Xianguang Meng;Dr. Tao Wang;Dr. Lequan Liu;Dr. Shuxin Ouyang;Dr. Peng Li;Huilin Hu;Dr. Tetsuya Kako;Dr. Hideo Iwai;Dr. Akihiro Tanaka; Jinhua Ye

Angewandte Chemie 2014 Volume 126( Issue 43) pp:11662-11666

Publication Date(Web):

DOI:10.1002/ange.201404953

Abstract

The photothermal conversion of CO₂ provides a straightforward and effective method for the highly efficient production of solar fuels with high solar-light utilization efficiency. This is due to several crucial features of the Group VIII nanocatalysts, including effective energy utilization over the whole range of the solar spectrum, excellent photothermal performance, and unique activation abilities. Photothermal CO₂ reaction rates (mol h⁻¹ g⁻¹) that are several orders of magnitude larger than those obtained with photocatalytic methods (μmol h⁻¹ g⁻¹) were thus achieved. It is proposed that the overall water-based CO₂ conversion process can be achieved by combining light-driven H₂ production from water and photothermal CO₂ conversion with H₂. More generally, this work suggests that traditional catalysts that are characterized by intense photoabsorption will find new applications in photo-induced green-chemistry processes.

Innentitelbild: Photothermal Conversion of CO2 into CH4 with H2 over GroupVIII Nanocatalysts: An Alternative Approach for Solar Fuel Production (Angew. Chem. 43/2014)

Co-reporter:Xianguang Meng;Dr. Tao Wang;Dr. Lequan Liu;Dr. Shuxin Ouyang;Dr. Peng Li;Huilin Hu;Dr. Tetsuya Kako;Dr. Hideo Iwai;Dr. Akihiro Tanaka; Jinhua Ye

Angewandte Chemie 2014 Volume 126( Issue 43) pp:

Publication Date(Web):

DOI:10.1002/ange.201408035

Inside Cover: Photothermal Conversion of CO2 into CH4 with H2 over GroupVIII Nanocatalysts: An Alternative Approach for Solar Fuel Production (Angew. Chem. Int. Ed. 43/2014)

Co-reporter:Xianguang Meng;Dr. Tao Wang;Dr. Lequan Liu;Dr. Shuxin Ouyang;Dr. Peng Li;Huilin Hu;Dr. Tetsuya Kako;Dr. Hideo Iwai;Dr. Akihiro Tanaka; Jinhua Ye

Angewandte Chemie International Edition 2014 Volume 53( Issue 43) pp:

Publication Date(Web):

DOI:10.1002/anie.201408035

Photothermal Conversion of CO2 into CH4 with H2 over GroupVIII Nanocatalysts: An Alternative Approach for Solar Fuel Production

Co-reporter:Xianguang Meng;Dr. Tao Wang;Dr. Lequan Liu;Dr. Shuxin Ouyang;Dr. Peng Li;Huilin Hu;Dr. Tetsuya Kako;Dr. Hideo Iwai;Dr. Akihiro Tanaka; Jinhua Ye

Angewandte Chemie International Edition 2014 Volume 53( Issue 43) pp:11478-11482

Publication Date(Web):

DOI:10.1002/anie.201404953

Abstract

The photothermal conversion of CO₂ provides a straightforward and effective method for the highly efficient production of solar fuels with high solar-light utilization efficiency. This is due to several crucial features of the Group VIII nanocatalysts, including effective energy utilization over the whole range of the solar spectrum, excellent photothermal performance, and unique activation abilities. Photothermal CO₂ reaction rates (mol h⁻¹ g⁻¹) that are several orders of magnitude larger than those obtained with photocatalytic methods (μmol h⁻¹ g⁻¹) were thus achieved. It is proposed that the overall water-based CO₂ conversion process can be achieved by combining light-driven H₂ production from water and photothermal CO₂ conversion with H₂. More generally, this work suggests that traditional catalysts that are characterized by intense photoabsorption will find new applications in photo-induced green-chemistry processes.

Synergistic effect of Au and Rh on SrTiO3 in significantly promoting visible-light-driven syngas production from CO2 and H2O

Co-reporter:Dewang Li, Shuxin Ouyang, Hua Xu, Da Lu, Ming Zhao, Xueliang Zhang and Jinhua Ye

Chemical Communications 2016 - vol. 52(Issue 35) pp:NaN5992-5992

Publication Date(Web):2016/03/31

DOI:10.1039/C6CC00836D

A novel photocatalyst constructed by Rh, Au, and SrTiO3 was developed to realize syngas photosynthesis from low-cost CO2 and H2O feedstock under visible-light irradiation. The synergistic effect of Rh and Au on SrTiO3 contributed to a 22- and 153-fold photoactivity magnification for syngas yield in contrast to Au@SrTiO3 and Rh@SrTiO3 samples, respectively.

Modulation of sulfur partial pressure in sulfurization to significantly improve the photoelectrochemical performance over the Cu2ZnSnS4 photocathode

Co-reporter:Yuanfang Zhang, Shuxin Ouyang, Qing Yu, Peng Li and Jinhua Ye

Chemical Communications 2015 - vol. 51(Issue 74) pp:NaN14059-14059

Publication Date(Web):2015/07/28

DOI:10.1039/C5CC04812E

Cu2ZnSnS4 photocathodes with excellent photoelectrochemical properties were fabricated via a facile method of adjusting the sulfur partial pressure in a semi-closed system, which achieved a maximum photocurrent-density of 1.8 mA cm−2 under irradiation of a solar simulator which is 9-fold larger than that synthesized in an open system.

In situ surface alkalinized g-C3N4 toward enhancement of photocatalytic H2 evolution under visible-light irradiation

Co-reporter:Yunxiang Li, Hua Xu, Shuxin Ouyang, Da Lu, Xin Wang, Defa Wang and Jinhua Ye

Journal of Materials Chemistry A 2016 - vol. 4(Issue 8) pp:NaN2950-2950

Publication Date(Web):2015/08/05

DOI:10.1039/C5TA05128B

Surface-alkalinization over g-C3N4 was realized by an in situ synthesis approach of introducing KCl and NH4Cl during the polymerization of melamine. The characterization of the Fourier transform-infrared spectrum, X-ray photoelectron spectrum, and electron spin resonance spectrum over the sample synthesized in the presence of KCl/NH4Cl and other reference samples indicated that the K ions played an essential role in breaking the periodic chemical structure of g-C3N4 and meanwhile the trace amount of H2O in melamine could supply OH ions to graft hydroxyl groups. The NH4Cl mainly contributed to exfoliation of layered g-C3N4 particles and pushing negative shift of the conduction-band level based on the measurements of the BET surface area and valence-band X-ray photoelectron spectrum. An optimal sample, g–C3N4–KCl/0.1 g NH4Cl (CN–KCl/0.1 g NH4Cl), achieved a more than 14-fold enhancement in photocatalytic H2 evolution under visible-light irradiation compared with the pristine g-C3N4. The enhanced photocatalytic efficiency could be attributed to the fact that the surface hydroxyl groups and the more negative conduction-band level can promote the separation of photocarriers and offer a stronger potential for water reduction, respectively.