Understanding Energy Conversion and Loss Mechanisms in Ternary Metal Oxide Photoelectrodes: The Case of Copper Vanadate

2017 ◽  
Author(s):  
Chang-Ming Jiang ◽  
Gideon Segev ◽  
Lucas H. Hess ◽  
Guiji Liu ◽  
Gregory Zaborski ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Surface States ◽  
Photocurrent Density ◽  
Absorption Length ◽  
Sputtering Deposition ◽  
Elemental Ratios ◽  
Onset Potential ◽  
Photocurrent Spectroscopy ◽  
Ternary Metal ◽  
Copper Vanadate

Essential photoelectrochemical (PEC) functionalities are systematically analyzed on a series of copper vanadate photoanodes with different Cu:V elemental ratios. Homogeneous, highly continuous, and phase-pure thin films of <i>β</i>-Cu<sub>2</sub>V<sub>2</sub>O<sub>7</sub>, <i>γ</i>-Cu<sub>3</sub>V<sub>2</sub>O<sub>8</sub>, Cu<sub>11</sub>V<sub>6</sub>O<sub>26</sub> and Cu<sub>5</sub>V<sub>2</sub>O<sub>10</sub> are grown via reactive co-sputtering deposition and then evaluated for their performances in light-driven oxygen evolution reaction (OER). Despite all four compounds have similar 1.8 – 2.0 eV bandgaps, Cu-rich phases are found to exhibit shorted absorption length in addition to higher charge separation efficiencies at the semiconductor/electrolyte junction. In the presence of sacrificial hole acceptor, the superior bulk properties of Cu<sub>5</sub>V<sub>2</sub>O<sub>10</sub> photoanode translate to the most cathodic (0.67 V vs. RHE) onset potential and a 206 μA/cm<sup>2</sup> photocurrent density that is four times higher than <i>β</i>-Cu<sub>2</sub>V<sub>2</sub>O<sub>7</sub> at 1.23 V. vs. RHE. Nevertheless, the sluggish OER kinetics competes with carrier recombination through Cu-associated surface states, and transient photocurrent spectroscopy quantitatively reveals the deterioration of surface catalytic activity with increasing Cu:V elemental ratio. This comprehensive analysis of PEC characteristics – light absorption, carrier separation, and heterogeneous charge transfer – not only gives insights into functional roles of individual elements in ternary metal oxide photoanodes, but also provides strategies for rational discovery, design, and engineering of new photoelectrode materials for solar fuel production.

Understanding Energy Conversion and Loss Mechanisms in Ternary Metal Oxide Photoelectrodes: The Case of Copper Vanadate

2017 ◽  
Author(s):  
Chang-Ming Jiang ◽  
Gideon Segev ◽  
Lucas H. Hess ◽  
Guiji Liu ◽  
Gregory Zaborski ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Surface States ◽  
Photocurrent Density ◽  
Absorption Length ◽  
Sputtering Deposition ◽  
Elemental Ratios ◽  
Onset Potential ◽  
Photocurrent Spectroscopy ◽  
Ternary Metal ◽  
Copper Vanadate

Essential photoelectrochemical (PEC) functionalities are systematically analyzed on a series of copper vanadate photoanodes with different Cu:V elemental ratios. Homogeneous, highly continuous, and phase-pure thin films of <i>β</i>-Cu<sub>2</sub>V<sub>2</sub>O<sub>7</sub>, <i>γ</i>-Cu<sub>3</sub>V<sub>2</sub>O<sub>8</sub>, Cu<sub>11</sub>V<sub>6</sub>O<sub>26</sub> and Cu<sub>5</sub>V<sub>2</sub>O<sub>10</sub> are grown via reactive co-sputtering deposition and then evaluated for their performances in light-driven oxygen evolution reaction (OER). Despite all four compounds have similar 1.8 – 2.0 eV bandgaps, Cu-rich phases are found to exhibit shorted absorption length in addition to higher charge separation efficiencies at the semiconductor/electrolyte junction. In the presence of sacrificial hole acceptor, the superior bulk properties of Cu<sub>5</sub>V<sub>2</sub>O<sub>10</sub> photoanode translate to the most cathodic (0.67 V vs. RHE) onset potential and a 206 μA/cm<sup>2</sup> photocurrent density that is four times higher than <i>β</i>-Cu<sub>2</sub>V<sub>2</sub>O<sub>7</sub> at 1.23 V. vs. RHE. Nevertheless, the sluggish OER kinetics competes with carrier recombination through Cu-associated surface states, and transient photocurrent spectroscopy quantitatively reveals the deterioration of surface catalytic activity with increasing Cu:V elemental ratio. This comprehensive analysis of PEC characteristics – light absorption, carrier separation, and heterogeneous charge transfer – not only gives insights into functional roles of individual elements in ternary metal oxide photoanodes, but also provides strategies for rational discovery, design, and engineering of new photoelectrode materials for solar fuel production.

scholarly journals Highly Active Deficient Ternary Sulfide Photoanode for Photoelectrochemical Water Splitting

2020 ◽  
Author(s):  
Haimei Wang ◽  
Yuguo Xia ◽  
Haiping Li ◽  
Xiang Wang ◽  
Yuan Yu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Active Sites ◽  
High Efficiency ◽  
Theoretical Calculations ◽  
Metal Sulfide ◽  
Surface States ◽  
Photocurrent Density ◽  
Highly Active ◽  
Ternary Sulfide ◽  
Ternary Metal

<div>The exploration of photoanode materials with high efficiency and stability is the </div><div>eternal pursuit for the realization of practically solar-driven photoelectrochemical </div><div>water splitting. Here we develop a novel deficient ternary metal sulfide (CdIn2S4) </div><div>as photoanode, and its PEC performance is significantly enhanced by introducing </div><div>surface S vacancies, achieving a photocurrent density of 5.73 mA cm-2 at 1.23 V vs. </div><div>RHE and 1 Sun and an applied bias photon-to-current efficiency of 2.49% at 0.477 </div><div>V vs. RHE, which, to the best of our knowledge, are the record-high values for a </div><div>single sulfide photon absorber to date. The experimental characterizations and </div><div>theoretical calculations highlight the enhanced effect of surface S vacancies on the </div><div>interfacial charge separation and transfer kinetics, and also demonstrate the </div><div>restrained surface states distribution and the transformation of active sites after </div><div>introducing surface S vacancies. This work may inspire more excellent work on </div><div>developing sulfide-based photoanodes. </div>

scholarly journals Highly Active Deficient Ternary Sulfide Photoanode for Photoelectrochemical Water Splitting

2020 ◽  
Author(s):  
Haimei Wang ◽  
Yuguo Xia ◽  
Haiping Li ◽  
Xiang Wang ◽  
Yuan Yu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Active Sites ◽  
High Efficiency ◽  
Theoretical Calculations ◽  
Metal Sulfide ◽  
Surface States ◽  
Photocurrent Density ◽  
Highly Active ◽  
Ternary Sulfide ◽  
Ternary Metal

<div>The exploration of photoanode materials with high efficiency and stability is the </div><div>eternal pursuit for the realization of practically solar-driven photoelectrochemical </div><div>water splitting. Here we develop a novel deficient ternary metal sulfide (CdIn2S4) </div><div>as photoanode, and its PEC performance is significantly enhanced by introducing </div><div>surface S vacancies, achieving a photocurrent density of 5.73 mA cm-2 at 1.23 V vs. </div><div>RHE and 1 Sun and an applied bias photon-to-current efficiency of 2.49% at 0.477 </div><div>V vs. RHE, which, to the best of our knowledge, are the record-high values for a </div><div>single sulfide photon absorber to date. The experimental characterizations and </div><div>theoretical calculations highlight the enhanced effect of surface S vacancies on the </div><div>interfacial charge separation and transfer kinetics, and also demonstrate the </div><div>restrained surface states distribution and the transformation of active sites after </div><div>introducing surface S vacancies. This work may inspire more excellent work on </div><div>developing sulfide-based photoanodes. </div>

Preparation of Sn doped SiO2thin films by magnetron sputtering deposition using metal and metal-oxide powder targets

2018 ◽  
Vol 58 (SA) ◽  
pp. SAAD04 ◽  
Author(s):  
Hiroharu Kawasaki ◽  
Tamiko Ohshima ◽  
Yoshihito Yagyu ◽  
Takeshi Ihara ◽  
Masanori Shinohara ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Metal Oxide ◽  
Oxide Powder ◽  
Sputtering Deposition ◽  
Metal Oxide Powder

Understanding the role of co-catalysts on silicon photocathodes using intensity modulated photocurrent spectroscopy

2017 ◽  
Vol 19 (43) ◽  
pp. 29653-29659 ◽  
Author(s):  
James E. Thorne ◽  
Yanyan Zhao ◽  
Da He ◽  
Shizhao Fan ◽  
Srinivas Vanka ◽  
...  
Keyword(s):  
Onset Potential ◽  
Co Catalysts ◽  
Intensity Modulated ◽  
Photocurrent Spectroscopy ◽  
Intensity Modulated Photocurrent Spectroscopy

IMPS shows that reducing recombination at low applied potentials is crucial in maximizing the onset potential for HER.

Nonlinear nanoelectrodynamics of a Weyl metal

2021 ◽  
Vol 118 (48) ◽  
pp. e2116366118
Author(s):  
Yinming Shao ◽  
Ran Jing ◽  
Sang Hoon Chae ◽  
Chong Wang ◽  
Zhiyuan Sun ◽  
...  
Keyword(s):  
Electric Fields ◽  
Mirror Symmetry ◽  
Density Functional ◽  
Near Field ◽  
Surface States ◽  
Real Space ◽  
Resonance Structure ◽  
Nonlinear Conductivity ◽  
Weyl Semimetal ◽  
Photocurrent Spectroscopy

Chiral Weyl fermions with linear energy-momentum dispersion in the bulk accompanied by Fermi-arc states on the surfaces prompt a host of enticing optical effects. While new Weyl semimetal materials keep emerging, the available optical probes are limited. In particular, isolating bulk and surface electrodynamics in Weyl conductors remains a challenge. We devised an approach to the problem based on near-field photocurrent imaging at the nanoscale and applied this technique to a prototypical Weyl semimetal TaIrTe4. As a first step, we visualized nano-photocurrent patterns in real space and demonstrated their connection to bulk nonlinear conductivity tensors through extensive modeling augmented with density functional theory calculations. Notably, our nanoscale probe gives access to not only the in-plane but also the out-of-plane electric fields so that it is feasible to interrogate all allowed nonlinear tensors including those that remained dormant in conventional far-field optics. Surface- and bulk-related nonlinear contributions are distinguished through their “symmetry fingerprints” in the photocurrent maps. Robust photocurrents also appear at mirror-symmetry breaking edges of TaIrTe4 single crystals that we assign to nonlinear conductivity tensors forbidden in the bulk. Nano-photocurrent spectroscopy at the boundary reveals a strong resonance structure absent in the interior of the sample, providing evidence for elusive surface states.

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