@article {1082, title = {Catalysts in electro-, photo- and photoelectrocatalytic CO2 reduction reactions}, journal = {Journal of Photochemistry and Photobiology C: Photochemistry Reviews}, year = {2019}, abstract = {

Published on March 2nd, 2019. Carbon dioxide (CO2) is regarded as a main contributor to the greenhouse effect. As a potential strategy to mitigate its negative impacts, the reduction of CO2 is environmentally critical, economically meaningful and scientifically challenging. Being both thermodynamically and kinetically unfavored, CO2 reduction requires catalysts as a crucial component irrespective of the reaction modes, be it electrocatalytic, photoelectrocatalytic or photocatalytic. In an effort to systematically review the types of catalysts that have been studied for CO2 reduction, we categorize them into two major groups: those being activated by external sources and those being photoexcited and activated themselves. Attention is focused on the detailed mechanisms for each group by which the reduction of CO2 proceeds, yielding a summary of the guiding principles for catalyst designs. This review highlights the importance of mechanistic studies, which permits us to discuss our perspectives on potential directions of catalyst investigation for future catalytic CO2 reduction research.

}, issn = {1389-5567}, doi = {10.1016/j.jphotochemrev.2019.02.002}, url = {http://www.sciencedirect.com/science/article/pii/S1389556718300674}, author = {Yawen Wang and Da He and Hongyu Chen and Dunwei Wang} } @article {1084, title = {Dependence of interface energetics and kinetics on catalyst loading in a photoelectrochemical system}, journal = {Nano Research}, year = {2019}, abstract = {

Published on March 11th, 2019. Solar hydrogen production by the photoelectrochemical method promises a means to store solar energy. While it is generally understood that the process is highly sensitive to the nature of the interface between the semiconductor and the electrolyte, a detailed understanding of this interface is still missing. For instance, few prior studies have established a clear relationship between the interface energetics and the catalyst loading amount. Here we aim to study this relationship on a prototypical Si-based photoelectrochemical system. Two types of interfaces were examined, one with GaN nanowires as a protection layer and one without. It was found that when GaN was present, higher Pt loading (\> 0.1 μg/cm2) led to not only better water reduction (and, hence, hydrogen evolution) kinetics but also more favorable interface energetics for greater photovoltages. In the absence of the protection layer, by stark contrast, increased Pt loading exhibited no measurable influence on the interface energetics, and the main difference was observed only in the hydrogen evolution kinetics. The study sheds new light on the importance of interface engineering for further improvement of photoelectrochemical systems, especially concerning the role of catalysts and protection layers.

}, issn = {1998-0000}, doi = {10.1007/s12274-019-2346-3}, url = {https://doi.org/10.1007/s12274-019-2346-3}, author = {Yumin He and Srinivas Vanka and Tianyue Gao and Da He and Jeremy Espano and Yanyan Zhao and Qi Dong and Chaochao Lang and Yongjie Wang and Thomas W. Hamann and Zetian Mi and Dunwei Wang} } @article {1090, title = {Thin film photoelectrodes for solar water splitting}, journal = {Chemical Society Reviews}, volume = {48}, year = {2019}, pages = {2182-2215}, abstract = {

Published on April 1st, 2019. Photoelectrochemical (PEC) water splitting has been intensively studied in the past decades as a promising method for large-scale solar energy storage. Among the various issues that limit the progress of this field, the lack of photoelectrode materials with suitable properties in all aspects of light absorption, charge separation and transport, and charge transfer is a key challenge, which has attracted tremendous research attention. A large variety of compositions, in different forms, have been tested. This review aims to summarize efforts in this area, with a focus on materials-related considerations. Issues discussed by this review include synthesis, optoelectronic properties, charge behaviors and catalysis. In the recognition that thin-film materials are representative model systems for the study of these issues, we elected to focus on this form, so as to provide a concise and coherent account on the different strategies that have been proposed and tested. Because practical implementation is of paramount importance to the eventual realization of using solar fuel for solar energy storage, we pay particular attention to strategies proposed to address the stability and catalytic issues, which are two key factors limiting the implementation of efficient photoelectrode materials. To keep the overall discussion focused, all discussions were presented within the context of water splitting reactions. How the thin-film systems may be applied for fundamental studies of the water splitting chemical mechanisms and how to use the model system to test device engineering design strategies are discussed.

}, issn = {1460-4744}, doi = {10.1039/C8CS00868J}, url = {https://pubs.rsc.org/en/content/articlelanding/2019/cs/c8cs00868j}, author = {Yumin He and Thomas Hamann and Dunwei Wang} } @article {1088, title = {Metallic nanocatalysts for electrochemical CO2 reduction in aqueous solutions}, journal = {Journal of Colloid and Interface Science}, volume = {527}, year = {2018}, pages = {95-106}, abstract = {

Published on October 1st, 2018. How to effectively and efficiently reduce carbon dioxide (CO2) to value-added chemicals represent a frontier in catalysis research. Due to the high activation energy needs and the endothermic nature of CO2 reduction, the reactions are difficult to carry out. When H2O is present, hydrogen evolution reactions (HER) often compete favorably with CO2 reduction reactions. For these reactions, catalysts are of critical importance to CO2 reduction. In this article, we review the various metal nanocatalysts for electrochemical CO2 reduction (ECR) reactions. In recognition of the importance of H2O to CO2 reduction, we focus our discussions on systems in aqueous solutions. Nanostructured metal catalysts are chosen for the discussions because they represent the most effective catalysts for ECR. After a brief introduction of the fundamental principles of ECR, we devote the rest of the article on the discussions of various types of nanostructured metallic catalysts, which are categorized by their compositions and working mechanisms. Lastly, strategies for improving reaction efficiency and selectivity are discussed.

}, issn = {0021-9797}, doi = {10.1016/j.jcis.2018.05.041}, url = {http://www.sciencedirect.com/science/article/pii/S0021979718305538}, author = {Yuanxing Wang and Cailing Niu and Dunwei Wang} } @article {1091, title = {Toward Practical Solar Hydrogen Production}, journal = {Chem}, volume = {4}, year = {2018}, month = {03/2018}, pages = {405-408}, abstract = {

Published on March 8th, 2018. Two articles recently published in Joule represent efforts in material discovery and new engineering for practical solar hydrogen production. Wong and colleagues improved the solar hydrogen production performance of Cu2ZnSnS4 by Cd substitution, and Domen and co-workers presented a panel design to take advantage of particulate Al-doped SrTiO3 photocatalysts for overall water splitting.

}, issn = {2451-9294}, doi = {10.1016/j.chempr.2018.02.013}, url = {http://www.sciencedirect.com/science/article/pii/S2451929418300743}, author = {Yumin He and Dunwei Wang} }