Query: challenge and perspective of heterogeneous photocatalysts

Candidate papers:

abstract: There is increasing interest in developing artificial systems that can mimic natural photosynthesis to directly harvest and convert solar energy into usable or storable energy resources. Photocatalysis, in which solar photons are used to drive redox reactions to produce chemical fuel, is the central process to achieve this goal. Despite significant efforts to date, a practically viable photocatalyst with sufficient efficiency, stability and low cost is yet to be demonstrated. It is often difficult to simultaneously achieve these different performance metrics with a single material component. The heterogeneous photocatalysts with multiple integrated functional components could combine the advantages of different components to overcome the drawbacks of single component photocatalysts. A wide range of heterostructures, including metal/semiconductor, semiconductor/semiconductor, molecule/semiconductor and multi heteronanostructures, have been explored for improved photocatalysts by increasing the light absorption, promoting the charge separation and transportation, enhancing the redox catalytic activity and prolonging the functional life time. The present review gives a concise overview of heterogeneous photocatalysts with a focus on the relationship between the structural architecture and the photocatalytic activity and stability.
author_names: Yongquan Qu

Xiangfeng Duan
title: Progress, challenge and perspective of heterogeneous photocatalysts.
venue: Chemical Society reviews
year: 2013

author_names: Yongquan Qu

Xiangfeng Duan
title: Progress, Challenge and Perspective of Heterogeneous Photocatalysts
year: 2013

abstract: This paper offers a perspective on inner sphere heterogeneous electron transfer reactions and electrocatalysis as it is applied to electrochemical energy conversion systems. Fundamental concepts and an overview of past approaches to studies of these types of reactions are discussed. A method for the discovery of new electrocatalysts (for example, ones for the oxygen reduction reaction) and photocatalysts (for solar energy conversion to fuels) based on scanning electrochemical microscopy is briefly described, as well as new surface interrogation techniques for quantifying intermediates.
author_names: Allen J Bard
title: Inner sphere heterogeneous electrode reactions. Electrocatalysis and photocatalysis: the challenge.
venue: Journal of the American Chemical Society
year: 2010

abstract: Abstract This perspective provides an insight to the possibility of adopting hydrogen as a key energy carrier and fuel source, through Photocatalytic water splitting in the near future. The need of green and clean energy is increasing to overcome the growing demand of sustainable energy throughout globe, owing to CO2 emission using fossil fuels. To generate highly efficient and cost competitive hydrogen, the semiconductor based heterojunction nanomaterials have gained tremendous consideration as a promising way. Currently, the efficiency for hydrogen generation through UV Vis active photocatalysts is relatively low. The key issues are found to be poor separation of photogenerated electron/hole, less surface area, and low absorption region of electromagnetic spectrum. Such issues arise due to inappropriate band edge potentials and large bandgap of present catalyst. A lot of schemes has been devoted to design and fabricate efficient photocatalysts for improved photocatalytic performance in recent years. However, it seems still a challenge and imperative to greatly comprehend the fundamental aspects, photocatalysis and transfer mechanisms for complete deployment of electron/hole pairs. Further, to produce hydrogen to a larger extent through photocatalytic water splitting, the photocatalyst has been modified through co catalysts/dopants using numerous techniques including the Z scheme, hybridization, crystallinity, morphology, tuning of band edge positions, reduction of the band gap, surface structure etc. such that these heterogeneous photocatalysts may have ability to absorb enough light in the UV VIS IR region. This type of heterogeneous photocatalysts has the ability to improve the rate of efficiency for hydrogen evolution through absorption of sufficient light of solar spectrum and enhance the separation of charge carriers by inhibiting recombination of electron/hole pairs. We surmise that taking into account the aforesaid factors should support in scheming an efficient photocatalysts for hydrogen production through water splitting, eventually prompting technological developments in this field.
author_names: M B Tahir

Abdullah M Asiri

Tasmia Nawaz
title: A perspective on the fabrication of heterogeneous photocatalysts for enhanced hydrogen production
year: 2020

abstract: Heterogeneous photocatalysis is a promising strategy for addressing the worldwide environmental pollution and energy shortage issues. However, unlike TiO2 with good photostability, the intrinsic drawback of photoinduced decomposition, i.e. photocorrosion, of semiconductors significantly challenges durable photocatalysis. In this review, the photocorrosion mechanisms of typical semiconductors and different characterization methods proposed for monitoring the photocorrosion process of semiconductor based composite photocatalysts are elaborated. Dedicated emphasis is put on the strategies for improving the anti photocorrosion property of semiconductor based photocatalysts, including modifying the crystal structure or morphology of semiconductors, doping with heteroatoms, hybridizing with various semiconductors and/or cocatalysts, and regulating the photocatalytic reaction conditions. Finally, we cast a personal prospect on the future development of the rational design of corrosion controlled semiconductor b.
author_names: Bo Weng

Ming-Yu Qi

Chuang Han

Zi-Rong Tang

Yi-Jun Xu
title: Photocorrosion Inhibition of Semiconductor Based Photocatalysts: Basic Principle, Current Development, and Future Perspective
venue: ACS Catalysis
year: 2019

abstract: Abstract Ammonia is the second most produced chemical worldwide that makes up 80% of nitrogen based fertilisers, which have supported approximately 27% of the world's population over the last century. The Haber Bosch process, which is the main process for producing ammonia, is extremely energy intensive and consumes around 1% of the world's energy. Additionally, it requires hydrogen gas as a reactant that is produced via steam reforming which emits carbon dioxide as a by product. Over 500 million tonnes of ammonia are produced per year via industrial processes which required 3 5% of total natural gas consumption worldwide and also accounted for 2% global energy usage. Therefore, more sustainable processes, such as electrocatalysis and photocatalysis, using electrons and the transfer of protons has been investigated. This review covers the most state of the art technologies used to produce ammonia via electrocatalysis and photocatalysis by comparing different electrolyte systems and electrocatalysts as well as discussing issues with these methods and possible solutions. In addition, substantial improvements to electrocatalysts and photocatalysts as well as methods to prevent both the promotion of the hydrogen evolution reaction and the decomposition of ammonia at higher temperatures are reviewed. Challenges and perspectives are discussed.
author_names: Ke Wang

Daniel J Smith

Ying Zheng
title: Electron driven heterogeneous catalytic synthesis of ammonia: Current states and perspective
year: 2018

abstract: Single atom photocatalysts have shown their compelling potential and arguably become the most active research direction in photocatalysis due to their fascinating strengths in enhancing light harvesting, charge transfer dynamics, and surface reactions of a photocatalytic system. While numerous comprehensions about the single atom photocatalysts have recently been amassed, advanced characterization techniques and vital theoretical studies are strengthening our understanding on these fascinating materials, allowing us to forecast their working mechanisms and applications in photocatalysis. In this review, we begin by describing the general background and definition of the single atom photocatalysts. A brief discussion of the metal support interactions on the single atom photocatalysts is then provided. Thereafter, the current available characterization techniques for single atom photocatalysts are summarized. After having some fundamental understanding on the single atom photocatalysts, their advantages and applications in photocatalysis are discussed. Finally, we end this review with a look into the remaining challenges and future perspectives of single atom photocatalysts. We anticipate that this review will provide some inspiration for the future discovery of the single atom photocatalysts, manifestly stimulating the development in this emerging research area.
author_names: Chao Gao

Jingxiang Low

Ran Long

Tingting Kong

Junfa Zhu

Yujie Xiong
title: Heterogeneous Single Atom Photocatalysts: Fundamentals and Applications.
venue: Chemical reviews
year: 2020

abstract: Visible light responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources. This review summarizes the recent progress in the design and fabrication of visible light responsive photocatalysts via various synthetic strategies, including the modification of traditional photocatalysts by doping, dye sensitization, or by forming a heterostructure, coupled with p conjugated architecture, as well as the great efforts made within the exploration of novel visible light responsive photocatalysts. Background information on the fundamentals of heterogeneous photocatalysis, the pathways of visible light responsive photocatalysis, and the unique features of visible light responsive photocatalysts are presented. The photocatalytic properties of the resulting visible light responsive photocatalysts are also covered in relation to the water treatment, i.e. regarding the photocatalytic degradation of organic compounds and inorganic pollutants, as well as photocatalytic disinfection. Finally, this review concludes with a summary and perspectives on the current challenges faced and new directions in this emerging area of research.
author_names: Shuying Dong

Jing-lan Feng

Maohong Fan

Yunqing Pi

Limin Hu

Xiao Han

Menglin Liu

Jingyu Sun

Jianhui Sun
title: Recent developments in heterogeneous photocatalytic water treatment using visible light responsive photocatalysts: a review
year: 2015

abstract: Abstract In developing efficient heterogeneous photocatalysts, the design and fabrication of hierarchical semiconductors at the micro/nanometer scales have received much attention during the past decade due to their unique advantages in addressing the critical problems during photocatalysis. However, there are still many challenges in designing and constructing highly efficient hierarchical photocatalysts. Thus, in this review, we first systematically summarize and discusse the fundamentals and important interface engineering strategies of designing hierarchical photocatalysts, such as fabricating Z Scheme heterojunctions, constructing Schottky based heterojunctions, creating carbon based heterojunctions and designing multicomponent heterojunctions. Then, especially, the different surface modification approaches of hierarchical porous photocatalysts, including loading cocatalysts, exposing the reactive facets, introducing defects/heteroatoms, adding photosensitizers, are highlighted. Finally, the major conclusions are made regarding this promising class of heterogeneous photocatalysts, and some perspectives are given on its future development. Through studying the important advances on this topic, it may pave a new avenue for fabricating highly effective hierarchical semiconductors for various applications in photocatalysis, electrocatalysis, thermal catalysis and other fields.
author_names: Rongchen Shen

Chuanjia Jiang

Quanjun Xiang

Jun Xie

Xin Li
title: Surface and interface engineering of hierarchical photocatalysts
venue: Applied Surface Science
year: 2019

abstract: Titanate nanostructures are of great interest for catalytic applications because their high surface area and cation exchange capacity create the possibility to achieve high metal dispersion. Ion exchange allows titanate nanostructures to incorporate metal adatoms in their framework. Consequently, the curved layers contain a large amount of defect sites, typically oxygen vacancies and Ti3+ centers, which can make them promising photocatalysts, because the defect sites can trap photoelectrons or holes extending the lifetime of the excited state. Due to the large amount of defects, titanate nanotubes (TNT) can stabilize sub nanosized gold clusters, presumably in Au25 form. This perspective summarizes the previous results obtained in the photocatalytic transformation of methane in which the size of gold nanoclusters plays an important role. Photocatalytic measurements revealed that methane is active towards photo oxidation. Methane transforms mainly into hydrogen and, to a lesser extent, to ethane and ethanol. Based on recent additional results, we stress here that gold clusters (Au25) may be directly involved in the photo induced reactions, namely in the direct activation of the methane/Au25d+ complex during irradiation. Another new finding is that gold nanoparticles supported on TNT exhibit high catalytic activity in CO2 hydrogenation. Our results revealed fundamental differences in the reaction schemes as the products of the two routes are CO (thermal process) and CH4 (photocatalytic route) indicating the importance of photogenerated electron hole pairs in the reaction. The presence of gold nanoparticles on the surface has been found to have multiple roles. On the one hand, gold in nano and sub nano sizes promotes the adsorption and scission of reactants, important for both types of reactions. On the other hand, the gold support interface forms a rectifying Schottky contact that helps in the separation of photogenerated carriers, thus improving the utilization of electrons and holes in the reduction and oxidation steps, respectively. Furthermore, gold ions (Au+ in the cationic sites of the titanate lattice promote the photocatalytic transformation of formate (which is one of the intermediates) thus advancing the reaction further towards the fully reduced product. The explored reaction schemes may pave the road towards novel catalytic materials that can solve challenges associated with the activation of CH4 and CO2 and thus contribute to green chemistry.Graphical Abstract
author_names: Janos T Kiss

Akos Kukovecz

Zoltan Konya
title: Beyond Nanoparticles: The Role of Sub nanosized Metal Species in Heterogeneous Catalysis
venue: Catalysis Letters
year: 2019