Recent advances in earth-abundant photocatalyst materials for solar H₂ production

Kahng, Soojin,Yoo, Harin,Kim, Jung Hyeun Elsevier 2020 Advanced powder technology Vol.31 No.1

<P><B>Abstract</B></P> <P>Harvesting solar energy attracts great attention due to its abundant, clean, and permanent characteristics. Thus, photocatalysts have emerged as promising candidates for converting the solar energy to practically useful hydrogen molecules. Tremendous efforts have been devoted in developments of efficient photocatalysts for water splitting, but most of photocatalysts utilize noble metals to improve photocatalytic performance. Progress in photocatalyst materials for the hydrogen production coupled with a better understanding of the basic catalytic mechanisms has enabled better selection of catalytic nanomaterials with improved performance. In this review, we analyze the current state of the art in photocatalyst materials for photochemical hydrogen production through water splitting using earth-abundant materials. We also explore two main factors involved in both material morphology and sacrificial agent to further improve the activity, efficiency and stability of photocatalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Noble metal-free photocatalysts for solar hydrogen evolution. </LI> <LI> Doping, heterostructure photocatalysts for efficient catalytic performance. </LI> <LI> Metal oxide, metal sulfide, and carbon-materials for photocatalysts. </LI> <LI> Effects of catalyst morphology and sacrificial agents on photocatalysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrothermally synthesized Na₂Ti₃O₇ nanotube–V₂O₅ heterostructures with improved visible photocatalytic degradation and hydrogen evolution - Its photocorrosion suppression

Vattikuti, S.V. Prabhakar,Reddy, Police Anil Kumar,NagaJyothi, P.C.,Shim, Jaesool,Byon, Chan Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.740 No.-

<P><B>Abstract</B></P> <P>There is still a need to prepare heterostructure photocatalysts with high activity and recyclability but without using precious metals to reduce the cost of photocatalysts. Thus, a facile and simple method for the synthesis of a Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst via hydrothermal synthesis is reported herein. The chemical composition, morphology, and structural features of the photocatalyst were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N<SUB>2</SUB> adsorption–desorption specific surface area analysis (BET), and diffuse reflectance absorption (DRS) methods. It was observed that the specific surface area of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst increased with the incorporation of V<SUB>2</SUB>O<SUB>5</SUB>. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst was then used for the removal of rhodamine B (RhB) under simulated solar light irradiation. The Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst revealed excellent photocatalytic activity and photodegradation kinetics as compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. Furthermore, both the photoactivity and long-term stability of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst were superior to those of the pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotubes and V<SUB>2</SUB>O<SUB>5</SUB> photocatalysts. The excellent photocatalytic performance of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> nanotube–V<SUB>2</SUB>O<SUB>5</SUB> heterostructure photocatalyst can be ascribed to its high specific surface area (283.71 m<SUP>2</SUP>g<SUP>−1</SUP>), mesoporous structure, highly dispersed V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles, and hindrance of electron–hole pair recombination of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> due to the V<SUB>2</SUB>O<SUB>5</SUB> incorporation, which is proven by the photoelectrochemical results, including photocurrent and electron impendence spectroscopy results. In addition, during the study of photocatalytic hydrogen evolution, the hydrogen yield of the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite was 1.83 times that of pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB>, which also exhibited excellent photocatalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterojunction of Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs was developed via hydrothermal method. </LI> <LI> Visible photocatalytic RhB degradation studies were performed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> <LI> Improved degradation efficiency was observed over Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs/V<SUB>2</SUB>O<SUB>5</SUB> NPs when compared to pristine Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs. </LI> <LI> V<SUB>2</SUB>O<SUB>5</SUB> NPs were successfully utilized as cocatalyst for pollutant degradation. </LI> <LI> Charge recombination was diminished in the Na<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>7</SUB> NTs by the addition of V<SUB>2</SUB>O<SUB>5</SUB> NPs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Development of graphene based photocatalysts for CO₂ reduction to C₁ chemicals: A brief overview

Ali, Shahzad,Razzaq, Abdul,In, Su-Il Elsevier 2019 CATALYSIS TODAY - Vol.335 No.-

<P><B>Abstract</B></P> <P>Transformation of CO<SUB>2</SUB>, a notorious greenhouse gas, to solar fuels is a promising strategy to alleviate the interlinked issues of global warming, environmental pollution, and climatic changes. Additionally, CO<SUB>2</SUB> conversion to useful chemicals/fuels also possess a great potential to well match the energy demand in a sustainable manner. Hence, such exceptional benefits of harnessing CO<SUB>2</SUB>, by capitalizing sunlight, to valuable chemicals/fuels through photocatalysis, as one of the effective approach in the respective domain, have triggered great interest among researchers and scientific community. In this regard, utilization of customary and standard photocatalytic materials, specifically metal oxides like TiO<SUB>2</SUB>, are modified to provide enhanced performance, which is usually restricted due to limited intrinsic optical and physicochemical properties. To overcome such a critical issue of limited performance, several strategies like metals and non-metals doping, hetero-junctions, composites and nanostructures formation of photocatalytic materials have been investigated. Recently, with the invention of graphene and its derivatives, graphene based photocatalytic materials have been a topic of great interest, specifically for photocatalysts development and photocatalysis application. Graphene and its derivatives, due to their extraordinary physiochemical and electrical properties like high surface area, stability, anticorrosion capacity, photosensitivity, and excellent conductivity, can overcome constraints faced by traditional photocatalysts. Thus, Graphene based photocatalysts can be a feasible strategy to break new grounds in the field of photocatalytic CO<SUB>2</SUB> reduction (PCCR) to useful chemicals/ fuels, i.e. conversion of sunlight to fuels. Herein, a summarized overview is presented for the latest development in graphene-based photocatalysts, focusing various strategies and researches being investigated in relation to the, utility of graphene and its derivatives for solar fuels generation, particularly C<SUB>1</SUB> chemicals like CO, CH<SUB>4</SUB>, CH<SUB>3</SUB>OH, and insights to their role in improving efficacy of photocatalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photocatalytic CO<SUB>2</SUB> reduction contributes both to environment and renewable energy. </LI> <LI> Intrinsic photocatalyst performance is limited due to certain aspects. </LI> <LI> Graphene based photocatalysts are reviewed precisely. </LI> <LI> C<SUB>1</SUB> to C<SUB>2</SUB> transition is considered as a potential future perspective. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Feasibility of using a rotating packed bed in preparing coupled ZnO/SnO2 photocatalysts

Chia-Chang Lin,Yu-Ju Chiang 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4

In this work, coupled ZnO/SnO2 photocatalysts were prepared in a rotating packed bed (RPB) via coprecipitation. The precursors of coupled ZnO/SnO2 photocatalysts were formed from solutions of zinc sulfate, tin tetrachloride and sodium hydroxide. The calcinations of these precursors yielded coupled ZnO/SnO2 photocatalysts. The effect of calcination temperature on the characteristics and photocatalytic activity of coupled ZnO/SnO2 photocatalysts was studied. The photocatalytic activity of coupled ZnO/SnO2 photocatalysts was evaluated using the photocatalytic decolorization of methylene blue. The experimental results reveal that coupled ZnO/SnO2 photocatalysts that were obtained by calcination at 600 8C for 10 h were the most efficient in decolorizing methylene blue.

Photocatalysts based on Conjugated Polymer Nanomaterials Utilizing Visible and Near Infrared Light

박주현 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Recent development for photocatalysis utilizing conjugated polymers is broadly reviewed. Conjugated polymers are promising photocatalysts for utilizing full solar spectrum because they absorb a wide-range of solar spectrum and be active from visible even to near infrared range. They can be used as independent photocatalysts, nanostructured to enlarge active surface area, or hybridized with ultraviolet-active photocatalysts for efficient photocatalysis via energy transfer from conjugated polymers as photosensitizers to the photocatalysts. A new strategy to enhance the photostability of conjugated polymer nanomaterials will be presented.

플라즈마 및 직접 기상 불소화에 의해 제어된 산소결핍 불소화 WO₃ 광촉매의 광분해 특성

이혜련,이란은,김대섭,이영석,Lee, Hyeryeon,Lee, Raneun,Kim, Daesup,Lee, Young-Seak 한국공업화학회 2022 공업화학 Vol.33 No.2

To enhance the photocatalytic activities of WO₃ photocatalysts, fluorine doping was performed to induce the oxygen vacancies. Both plasma and direct vaper fluorination were carried out for fluorine doping, and photocatalytic activities were examined by using methylene blue dye. Oxygen vacancies of the plasma and direct vaper fluorinated WO₃ photocatalysts were measured to be 14.65 and 18.59%, which increased to about 23 and 56% at pristine WO₃ photocatalysts. The degradation efficiency of methylene blue was also determined about 1.7 and 3.4 times higher than pristine WO₃ photocatalysts, respectively, depending on oxygen vacancies increased. In addition, it was confirmed that the bandgap process energy decreased from 2.95 eV to 2.64 and 2.45 eV after fluorine doping. From this result, it is considered that the direct vaper fluorination has an advantage for increasing the photocatalytic activities of WO₃ compared to that of the plasma fluorination.

An overview of SnO2 based Z scheme heterojuctions: Fabrication, mechanism and advanced photocatalytic applications

Akshay Chawla,Anita Sudhaik,Pankaj Raizada,Aftab Aslam Parwaz Khan,Archana Singh,Quyet Van Le,Van Huy Nguyen,Adem Sreedhar,Saad M. Alshehri,Abdullah M. Asiri,Pardeep Singh 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-

Not just people, but all living species, desire a clean and green environment to live a happy and healthylife. However, in our ever-increasingly congested world, it is quite challenging. Excessive deforestation,factory smoke, various chemical compounds, agricultural chemicals, etc. all pollute our environmentseverely. Some of its adverse consequences include water contamination and a shortage of energy supplies. In recent times, photocatalysts have sparked tremendous attention as a means of addressing energydemands as well as environmental challenges (water pollution). For this, SnO2 and SnO2 based photocatalystshave gained a great attention due to its good photocatalytic ability. In the same way, SnO2-based Zschemephotocatalysts has extended significant interest to address these concerns due to its strong photocatalyticcharacteristics, energy savings, eco-friendliness, and lack of adverse health effects. Though, thephotocatalytic effectiveness of conventional SnO2 semiconductors, with their shortcomings, falls wellshort of the real requirements. The current review emphasizes on admirable properties and several synthesisprocesses of SnO2 which make it an ideal photocatalyst. This study also stresses the fundamentalshortcomings of SnO2 that restrict its utilization. The central section of this review is concentrated onSnO2-based Z-scheme photocatalysts and most recent significant research modification of Z-schemeSnO2-based photocatalysts. The photocatalytic applications of Z-scheme SnO2-based photocatalysts forpollutants removal, energy conversion, and water splitting are also summarized. In conclusion, we haveaddressed the challenges and future exploration of SnO2-based photocatalysts with a Z-scheme heterojunctiontype for pollutant degradation and energy conversion.

Understanding the relative efficacies and versatile roles of 2D conductive nanosheets in hybrid-type photocatalyst

Son, Suji,Lee, Jang Mee,Kim, Se-Jun,Kim, Hyejin,Jin, Xiaoyan,Wang, Kang Kyun,Kim, Minho,Hwang, Jeong Wook,Choi, Wonyong,Kim, Yong-Rok,Kim, Hyungjun,Hwang, Seong-Ju Elsevier BV 2019 Applied Catalysis B Vol.257 No.-

<P><B>Abstract</B></P> <P>Hybridization with conductive 2D nanosheets (NSs) attracts plenty of research activities because of its effectiveness for improving the photocatalyst performance of diverse semiconductors. Here, versatile roles of conductive NSs in hybrid-type photocatalysts are systematically investigated with three representative conductive 2D NSs to synthesize highly efficient visible light-active photocatalysts. Among several conductive NS-based nanohybrids, the RuO<SUB>2</SUB> NS-based nanohybrid exhibits the highest photocatalytic activities. Based on systematic spectroscopic analyses, polar RuO<SUB>2</SUB> NS appears to be more effective as electron reservoir, photosensitizer, cocatalyst and charge carrier pathway in hybrid-type photocatalyst than MoS<SUB>2</SUB> and graphene NSs. The high efficiency of RuO<SUB>2</SUB> NS as hybridization matrix is attributable to the high surface hydrophilicity, high surface bond polarity, and enhanced interfacial electronic coupling of this hydrophilic NS with semiconductor. The present study underscores that hydrophilic conductive metal oxide NS can act as the most efficient hybridization matrix for exploring high-performance photocatalysts with strong interfacial electronic coupling.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 2D conductive nanosheets play versatile roles in hybrid-type photocatalysts. </LI> <LI> Hybridization with conductive nanosheet remarkably enhances photocatalyst activity. </LI> <LI> Interfacial electronic coupling is the most crucial factor for hybrid-type photocatalyst. </LI> <LI> Hydrophilic metal oxide nanosheet is the most efficient hybridization matrix. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrogenated heterojunction of boron nitride and titania enables the photocatalytic generation of H₂ in the absence of noble metal catalysts

He, Zuoli,Kim, Chuhyung,Jeon, Tae Hwa,Choi, Wonyong Elsevier 2018 Applied Catalysis B Vol.237 No.-

<P><B>Abstract</B></P> <P>The increasing need for new materials capable of solar fuel production is central to the development of green energy economy. Utilizing solar energy for hydrogen generation is a great challenge due to inefficient light utilization and fast charge recombination. In this work, disorder-engineered black H-TiO<SUB>2</SUB>@BN with Ti-B chemically bonded interfaces was synthesized by employing BN nanosheets as the photocatalyst support. The hybridization of TiO<SUB>2</SUB> with BN and hydrogenated thermal treatment work synergistically to enable the photocatalytic H<SUB>2</SUB> production without noble metal cocatalysts. The hybrid photocatalyst markedly enhanced light absorption, significantly retarded charge pair recombination, facilitated interfacial electron transfer, and lowered interfacial charge transfer resistance. As a result, the photocatalytic H<SUB>2</SUB> production activity of H-TiO<SUB>2</SUB>@BN that consisted of earth-abundant elements only was comparable to that of Pt-TiO<SUB>2</SUB>. The present hybrid engineering for the efficient charge separation and transfer via the formation of the interfacial chemical bonds should provide a useful methodology for designing the new types of hybrid photocatalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Disorder-engineered black H-TiO<SUB>2</SUB>@BN with Ti-B chemically bonded interfaces was synthesized. </LI> <LI> Hybridization of TiO<SUB>2</SUB> with BN and the hydrogenated thermal treatment work synergistically to enable the photocatalytic H<SUB>2</SUB> production. </LI> <LI> Formation of the interfacial Ti-B bonds improves the visible light absorption and the charge transfer efficiency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Hydrogenated Heterojunction of Boron Nitride and Titania, disorder-engineered black H-TiO<SUB>2</SUB>@BN with Ti-B chemically bonded interfaces was synthesized by employing BN nanosheets as the photocatalyst support. The hybridization of TiO<SUB>2</SUB> with BN and the hydrogenated thermal treatment work synergistically to enable the photocatalytic H<SUB>2</SUB> production without noble metal cocatalysts. The hybrid photocatalysts markedly enhanced light absorption, significantly retarded charge pair recombination, facilitated interfacial electron transfer and lowered interfacial charge transfer resistance.</P> <P>[DISPLAY OMISSION]</P>

Hot Electron Transfer Kinetics in Aggregation-Induced Nanoscale Reactor

배주은,김영수 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Plasmonic metal nanoparticles have been received increasing attention as visible-light-driven photocatalysts due to their unique optical property by localized surface plasmon resonance (LSPR). However, the electron transfer kinetics of photocatalytic reactions in the colloidal system is limited by the diffusion of the chemical moieties to the vicinity of photocatalysts. To achieve the high-efficiency photocatalysts, It would be a key point that the diffusion length of chemical species for photochemical reaction needs to be shortened. To do this, we designed a nanoscale reactor, in which the chemical species can be confined closely near the photocatalysts, through the surface engineering of nanoparticles and a type of additive. We examined the electron transfer kinetics between the free-standing colloidal nanoparticle system and the colloidal nanoreactor system.