Analysis of Products from Photoelectrochemical Reduction of <sup>13</sup>CO<sub>2</sub> by GaN-Si Based Tandem Photoelectrode

Sekimoto, Takeyuki; Hashiba, Hiroshi; Shinagawa, Shuichi; Uetake, Yusuke; Deguchi, Masahiro; Yotsuhashi, Satoshi; Ohkawa, Kazuhiro

doi:10.1021/acs.jpcc.6b03840

Cited by 31 publications

(26 citation statements)

References 26 publications

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“…Moreover, the presented concept also clearly distinguishes itself from proof-of-concept approaches, demonstrating small-scale subassemblies for solardriven CO 2 reduction. 14,49,[55][56][57][58][59] The coupling of pure academic with engineered systems is urgently needed to mature CO 2 recycling processes and open the pathway towards a commercial application. This aspect is successfully addressed by the proposed concept.…”

Section: B Photoanode Composed Of Si Heterojunction Solar Cell and Nmentioning

confidence: 99%

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

Urbain

Tang

Carretero

et al. 2017

Energy Environ. Sci.

121

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The conversion of carbon dioxide (CO2) into value-added chemicals and fuels, preferably using renewable energy and earth-abundant materials, is considered a key priority for future energy research. In this work, a bias-free reactor device for the solar-driven conversion of CO2 to synthesis gas (syngas) has been developed. The integrated fluidic device consists of a cathode made of copper foam coated with low-cost nanosized zinc flakes as catalyst to perform the CO2 reduction reaction (CO2RR) to syngas, an adapted silicon heterojunction solar cell structure as photoanode with nickel foam as catalyst to facilitate the oxygen evolution reaction (OER), and a bipolar membrane separating the respective catholyte and anolyte compartments. The membrane allows for the operation of the catholyte and anolyte at different pH values. Stable and tunable hydrogen-to-carbon monoxide (H2:CO) ratios between 5 and 0.5 along with high CO Faradaic efficiencies of up to 85% and CO current densities of 39.4 mA cm-2 have been demonstrated. Under photoelectrolysis conditions, the photovoltage of the photoanode was varied between 0.6 V and 2.4 V by connecting up to four heterojunction solar cells in series, and thus reducing the overall cell voltage solely by solar energy utilization. Bias-free operation of the integrated device has been achieved under ambient conditions with active areas for CO2RR and OER, respectively, of 10 cm2. An operation current density of 5.0 mA cm-2 was measured under 100 mW cm-2 illumination of the complete device, which corresponds to a solar-to-syngas conversion efficiency of 4.3%.Postprint (author's final draft

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Section: B Photoanode Composed Of Si Heterojunction Solar Cell and Nmentioning

confidence: 99%

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

Urbain

Tang

Carretero

et al. 2017

Energy Environ. Sci.

121

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“…NiO cocatalyst improved not only the Energy Conversion Efficiency (ECE) of nitride photoelectrodes, but also their lifetime, which has been demonstrated to be at least 500 h 12 . It has also been confirmed that NiO/nitride photoelectrodes can be used to generate more complex byproducts than H 2 , such as formic acid and methane from CO 2 in artificial photosynthesis reactions 13 – 16 .…”

Section: Introductionmentioning

confidence: 92%

Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst

Velazquez-Rizo

Ohkawa

2020

Sci Rep

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nitrides are of particular interest in energy applications given their suitability to photocatalytically generate H 2 from aqueous solutions. However, one of the drawbacks of nitrides is the decomposition they suffer when used in photoelectrochemical cells. Here, we report the improvement of the catalytic performance and chemical stability of a Gan electrode when it is decorated with fe 2 o 3 particles compared with an undecorated electrode. our results show a higher reaction rate in the fe 2 o 3 /Gan electrode, and that photocorrosion marks take more than 20 times longer to appear on it. We also characterized the crystalline properties of the fe 2 o 3 particles with transmission electron microscopy. the results show that the fe 2 o 3 particles keep an epitaxial relationship with GaN that follows the fe 2 o 3 {0003}||Gan{0001} and fe 2 o 3 [1120]||Gan[1100] symmetry constraints. We also characterized an fe 2 o 3 (thin film)/GaN electrode, however it did not present any catalytic improvement compared with a bare GaN electrode. The epitaxial relationship found between the Fe 2 o 3 thin film and GaN exhibited the fe 2 o 3 {1120}||Gan{0002} and fe 2 o 3 [3300]||Gan[1120] symmetry constraints. The increasing energy demand of humankind and the negative environmental impact of the consumption of fossil fuels are driving the development of alternative energy sources. One of the candidates to substitute fossil fuels is H 2 , which can generate energy through its direct combustion or in fuel cells without creating pollution. However, the non-pollutant attributes of H 2 have been overshadowed by the lack of an environmentally friendly method for its manufacture. One alternative to sustainably generate H 2 is the photocatalytic water splitting using semiconductors 1. Nitrides have received considerable attention in this field because, as a result of their band gap tunability 2-8 , they can absorb most of the energy of the solar spectrum. After the first demonstration of photoelectrochemical (PEC) H 2 generation using GaN thin films as photoelectrodes 9 , and their subsequent improvement to perform chemical reactions without any external electrical bias 10 , the discovery of the NiO cocatalyst technology 11 greatly boosted the expectations of nitride-based photocatalysts. NiO cocatalyst improved not only the Energy Conversion Efficiency (ECE) of nitride photoelectrodes, but also their lifetime, which has been demonstrated to be at least 500 h 12. It has also been confirmed that NiO/nitride photoelectrodes can be used to generate more complex byproducts than H 2 , such as formic acid and methane from CO 2 in artificial photosynthesis reactions 13-16. The improvement of the catalytic activity of GaN photoanodes by using metals or metal oxides as cocatalysts can be attributed to the introduction of active sites by the metal or oxygen atoms. For example, in water splitting on metal oxides, the Oxygen Evolution Reaction (OER) mechanism has been described conventionally as a four proton-electron transfer reaction in the metal-sites...

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Section: Operational Considerationsmentioning

confidence: 99%

Solar‐Driven Electrochemical CO₂ Reduction with Heterogeneous Catalysts

Creissen

Fontecave

2020

Advanced Energy Materials

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solubility of CO 2 in aqueous electrolyte solution (≈30 × 10 −3 m), which leads to diffusion-limited current densities. Device engineering has addressed this issue through the development of flow cell configurations that overcome mass transport limitations of conventional H-cells, thus improving attainable current densities. [4][5][6][7] Another complication resides in the kinetic requirement for multiple electron and proton transfers, which results in high energy barriers for certain products, requiring efficient catalysts for high current densities. The similarity in thermodynamic potentials for different CO 2 R products (Table 1) means that product selectivity is a problem. Additionally, proton reduction is kinetically fast in aqueous conditions leading to competitive hydrogen generation. CO 2 R electrocatalysts have been developed to address this broad range of products that can be generated and the concomitant lack of selectivity.Although molecular electrocatalysts have demonstrated high selectivity for CO 2 R to C 1 products, [8] they currently suffer from short-term stability. [9] The most effective catalysts are those based on metallic or semiconducting materialsheterogeneous catalysts. Metallic catalysts in particular have shown high selectivity for: CO using Ag, Zn, and Au; formate using Sn, In, and Pb; and a range of multi-carbon products using Cu catalysts in EC systems. [10][11][12][13][14][15] Knowledge of how nanoscale properties and morphological effects influence specificity, has enabled systems to achieve high selectivity with competitive production rates. [13] For example, identifying key morphological attributes and alterations under operating conditions, [16][17][18][19][20][21][22] observing trends in size and facet-dependent selectivity, [23][24][25][26][27] and evaluating the impact of structuration on the local chemical environment, [28][29][30] all contribute to increased understanding of structure-activity relationships in CO 2 R. The type of catalyst employed therefore plays a large role in overall performance.EC CO 2 R devices can theoretically be coupled with any renewable electricity source, however, the direct integration of sunlight-driven processes is a desirable route to product formation. [31,32] An integrated approach avoids the need for grid access in remote locations, enabling direct on-site utilization, and reduces energy losses from current conversion. The additional costs in combining grid electricity with conventional electrolyzers has driven research toward the incorporation of increasingly affordable PV components. An additional benefit is the dual functionality of these devices that allows them to retain their The simultaneous mitigation of CO 2 emissions and direct generation of value-added chemicals has motivated research in solar-driven electrochemical CO 2 reduction. Here, devices incorporating heterogeneous catalysts that operate under bias-free aqueous conditions are categorized and compared, encompassing photoelectrochemical (PEC), photovoltaic-electrochemical ...

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Analysis of Products from Photoelectrochemical Reduction of ¹³CO₂ by GaN-Si Based Tandem Photoelectrode

Cited by 31 publications

References 26 publications

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst

Solar‐Driven Electrochemical CO₂ Reduction with Heterogeneous Catalysts

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Analysis of Products from Photoelectrochemical Reduction of 13CO2 by GaN-Si Based Tandem Photoelectrode

Cited by 31 publications

References 26 publications

A prototype reactor for highly selective solar-driven CO2reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

A prototype reactor for highly selective solar-driven CO2reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst

Solar‐Driven Electrochemical CO2 Reduction with Heterogeneous Catalysts

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Analysis of Products from Photoelectrochemical Reduction of ¹³CO₂ by GaN-Si Based Tandem Photoelectrode

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

A prototype reactor for highly selective solar-driven CO₂reduction to synthesis gas using nanosized earth-abundant catalysts and silicon photovoltaics

Solar‐Driven Electrochemical CO₂ Reduction with Heterogeneous Catalysts