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Journal ArticleDOI: 10.1039/D0NR08442E

Construction of a Z-scheme heterojunction for high-efficiency visible-light-driven photocatalytic CO2 reduction

04 Mar 2021-Nanoscale (The Royal Society of Chemistry)-Vol. 13, Iss: 8, pp 4359-4389
Abstract: The continuous growth of fossil fuel consumption and large amounts of CO2 emissions have caused global energy crisis and climate change. The employment of semiconductor photocatalysts to convert CO2 into value-added products has attracted extensive attention and research worldwide in recent years. However, it is difficult for a single-component semiconductor photocatalyst to achieve this goal efficiently due to its drawbacks, such as low quantum efficiency, limited surface area, limited number of active sites, the short lifetime of photogenerated carriers, poor long-term stability, and the weak redox ability of carriers. Fortunately, inspired by photosynthesis, the construction of an artificial Z-scheme heterojunction has brought a new dawn for the realization of this goal. The Z-scheme heterojunction has a high separation efficiency of electron-hole pairs with strong redox ability and a wide light response range. The abovementioned advantages make the Z-scheme heterojunction provide a great opportunity for the conversion of CO2 to value-added chemicals. This review concisely reports the progress of the Z-scheme heterojunction in the field of photocatalytic CO2 reduction in recent years, photocatalytic mechanism, choice of oxidation and reduction systems, strategies for improving efficiency, confirmation of the Z-scheme charge transport mechanism, problems and challenges, and the prospects for the future.

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10 results found

Journal ArticleDOI: 10.1016/J.CEJ.2021.131192
Na Zhang1, Qing Zhang1, Xu Chen1, Yang Li1  +5 moreInstitutions (2)
Abstract: Herein, the flexible self-supported Cu2O@Fe2O3@carbon cloth electrode (named as Cu2O@Fe2O3@CC) has been synthesized by a facile and scalable thermal method. This Cu2O@Fe2O3@CC-500 hierarchical assembly needs ultralow overpotential of 296 mV (for oxygen evolution reaction, OER) and 188 mV (for hydrogen evolution reaction, HER) to afford the 10 mA cm−2 current density, and with the Tafel slope of 66 mV dec−1 (for OER) and 59 mV dec−1 (for HER) in alkaline medium (1.0 M KOH), respectively. The assembled water electrolyzer using bifunctional Cu2O@Fe2O3@CC-500 as both anode and cathode exhibited high stability with a cell voltage of only 1.675 V at 10 mA cm−2. More interestingly, this composite also exhibited excellent photocatalytic performance in CO2 reduction. For the Cu2O@Fe2O3@CC-500, the CO yield attained 172.2 µmol·gcatalyst−1·h−1 under visible light irradiation. Based on the measurements and density functional theory (DFT) calculation, an enhanced OER kinetics and a plausible mechanism for CO2 photo-reduction have been proposed. Our study will open a special door to provide multifunctional phtoelectrocatalyst to be widely used in the clean energy field.

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Topics: Overpotential (56%), Water splitting (54%), Tafel equation (53%) ... show more

2 Citations

Open accessJournal ArticleDOI: 10.1016/J.APCATB.2021.120902
Krishnendu Das1, Ranjit Bariki1, Dibyananda Majhi1, Abtar Mishra1  +3 moreInstitutions (2)
Abstract: Facile fabrication of visible light responsive multicomponent heterostructure photocatalysts with synergistic photoelectron migration is an effective approach with potential application in water remediation and renewable energy generation. In this study, a series of ternary multi-heterojunction CdS/Bi20TiO32/Bi4Ti3O12 (CdSxBTC) photocatalysts were prepared by hydrothermal deposition of CdS nanoparticles (15–25 nm) over one pot combustion synthesized Bi20TiO32/Bi4Ti3O12 (BTC) nanostructures. Comprehensive characterization of the ternary composites revealed enhanced optical absorption, high interfacial contact, fast electron channelization and a prolonged excited state life time. The CdSxBTC composite materials displayed enhanced photocatalytic activity for endosulfan degradation (kapp value 6–12 times greater than pure semiconductors) and water splitting reaction (H2 production rate 1890 μmolg−1h−1 and apparent conversion efficiency 19%). The cell viability -study disclosed non-cytotoxic nature of the treated endosulfan solution. A synergistic Type-I bridged coupled Z-scheme electron migration process accounted for robust radical generation ability (•O2− and •OH) and photocatalytic activity of the ternary composites.

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Topics: Ternary operation (54%), Water splitting (53%), Photocatalysis (51%)

Journal ArticleDOI: 10.1016/J.CEJ.2021.132740
Wang Min1, Guoqiang Tan1, Huijun Ren1, Long Lv  +1 moreInstitutions (1)
Abstract: In this work, plasma Bi and oxygen vacancies (OVs) co-modified g-C3N4-x/Bi/Bi2O2(CO3)1-x(Br, I)x heterojunction was prepared via solvothermal reaction. The formation of OVs was promoted induced by polarization charge transfer, while the deposition of Bi was attributed to the esterification between CH3CH2OH and NaBiO3 and subsequent anoxic thermal reduction. The increased OVs concentration improved the adsorption performance of tetracycline (TC), meanwhile promoting the separation of hot carriers of plasma Bi by trapping hot electrons. The dissociated hot holes directly drove near-infrared (NIR) photocatalytic reaction. The deactivation of OVs in Bi2O2(CO3)1-x(Br, I)x was inhibited due to the deposition of Bi, and the Z-scheme mechanism was achieved with Bi as electron mediator. Hence, g-C3N4-x/Bi/Bi2O2(CO3)1-x(Br, I)x showed enhanced full-spectrum catalytic activity and excellent stability. 84.6%/70.0% and 79.33%/70.19% of TC and total organic carbon could be removed by the optimal heterojunction under simulated sunlight/NIR light irradiation, and the NO removal rate under visible light irradiation was as high as 76.7%. This work revealed the different roles of OVs and metal in defect-mediated heterojunction, and provided a feasible method to prepare full-spectrum response photocatalysts with high activity and stability.

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Open accessJournal ArticleDOI: 10.1016/J.JALLCOM.2021.162576
Anjli Sharma, Sanjeev Kumar Kanth1, Shishi Xu, Ni Han  +4 moreInstitutions (1)
Abstract: A highly potential visible light active g-C3N4/Bi4NbO8X (Cl, Br) heterojunction photocatalysts were constructed at the interface of the coupling between Bi4NbO8X (Cl, Br) and g-C3N4. The band gap value of heterojunctions g-C3N4/Bi4NbO8Br-20% (CNBNB-3) and g-C3N4/Bi4NbO8Cl-20% (CNBNC-3), and pristine materials g-C3N4 (CN), Bi4NbO8Cl and Bi4NbO8Br materials were analyzed to be 2.68 eV, 2.69 eV and 2.74 eV, 2.46 eV and 2.48 eV, respectively. The degradation performance of optimized CNBNC-3 and CNBNB-3 photocatalysts revealed much superior removal efficiency of 97% and 84% than the pristine material for rhodamine B. The synthesized photocatalysts maintained good recyclable stability after five consecutive cycles and potentially capable of pollutant degradation. The electrochemical impedance and photoluminescence spectroscopy revealed that the migration and separation efficiency of photogenerated charge carriers of photocatalyst were boosted, while reduced recombination rate was observed. The photocatalytic reaction mechanism also revealed the superoxide ·O 2 − and •OH radicals are the main active species responsible for the pollutant degradation.

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Topics: Photocatalysis (50%)

Open accessJournal ArticleDOI: 10.1016/J.JALLCOM.2021.162667
Zheng Xu1, Yuxing Shi1, Lingling Li1, Haoran Sun1  +5 moreInstitutions (2)
Abstract: Photocatalytic degradation of antibiotic pollutant from contaminated water is essential for environmental protection. Rational development and design of composite photocatalyst with high catalytic activity and stability plays an important role in the photocatalytic field. Herein, 2D/2D highly crystalline carbon nitride/δ-Bi2O3 (HCCN/BO) Z-scheme heterojunction photocatalyst was synthesized via a facile solvothermal strategy. Experimental results show that the optimal HCCN/BO-3 sample exhibits a ~ 90% degradation rate during the photocatalytic degradation of the tetracycline (TC) within 60 min. The enhancement of photocatalytic activity is mainly attributed to the two reasons as follows: (i) the formation of 2D/2D heterojunction shortens the distance of the carriers from the body to the surface and gives two kinds of semiconductors rich active sites, improving the production and separation efficiency of photogenerated active carriers; (ii) the transmission path of photo-induced electrons follows the Z-scheme that can effectively inhibit the recombination of electrons and holes, expand the wide band gap, and harvest more visible light, separate oxidation and reduction active sites to retain redox capacity. Finally, the intermediate in the degradation pathway is determined using liquid chromatography-series mass spectrometry (LC-MS), and the TC degradation pathway for the photocatalytic reaction process of this composite system is proposed.

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Topics: Photocatalysis (53%), Heterojunction (51%), Carbon nitride (51%)


188 results found

Journal ArticleDOI: 10.1002/ADMA.201400288
Peng Zhou1, Jiaguo Yu1, Mietek Jaroniec2Institutions (2)
01 Aug 2014-Advanced Materials
Abstract: The current rapid industrial development causes the serious energy and environmental crises. Photocatalyts provide a potential strategy to solve these problems because these materials not only can directly convert solar energy into usable or storable energy resources but also can decompose organic pollutants under solar-light irradiation. However, the aforementioned applications require photocatalysts with a wide absorption range, long-term stability, high charge-separation efficiency and strong redox ability. Unfortunately, it is often difficult for a single-component photocatalyst to simultaneously fulfill all these requirements. The artificial heterogeneous Z-scheme photocatalytic systems, mimicking the natural photosynthesis process, overcome the drawbacks of single-component photocatalysts and satisfy those aforementioned requirements. Such multi-task systems have been extensively investigated in the past decade. Especially, the all-solid-state Z-scheme photocatalytic systems without redox pair have been widely used in the water splitting, solar cells, degradation of pollutants and CO2 conversion, which have a huge potential to solve the current energy and environmental crises facing the modern industrial development. Thus, this review gives a concise overview of the all-solid-state Z-scheme photocatalytic systems, including their composition, construction, optimization and applications.

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1,556 Citations

Journal ArticleDOI: 10.1016/J.APSUSC.2016.07.030
Jiuqing Wen1, Jun Xie1, Xiaobo Chen2, Xin Li1Institutions (2)
Abstract: As one of the most appealing and attractive technologies, heterogeneous photocatalysis has been utilized to directly harvest, convert and store renewable solar energy for producing sustainable and green solar fuels and a broad range of environmental applications. Due to their unique physicochemical, optical and electrical properties, a wide variety of g-C3N4-based photocatalysts have been designed to drive various reduction and oxidation reactions under light irradiation with suitable wavelengths. In this review, we have systematically summarized the photocatalytic fundamentals of g-C3N4-based photocatalysts, including fundamental mechanism of heterogeneous photocatalysis, advantages, challenges and the design considerations of g-C3N4-based photocatalysts. The versatile properties of g-C3N4-based photocatalysts are highlighted, including their crystal structural, surface phisicochemical, stability, optical, adsorption, electrochemical, photoelectrochemical and electronic properties. Various design strategies are also thoroughly reviewed, including band-gap engineering, defect control, dimensionality tuning, pore texture tailoring, surface sensitization, heterojunction construction, co-catalyst and nanocarbon loading. Many important applications are also addressed, such as photocatalytic water splitting (H2 evolution and overall water splitting), degradation of pollutants, carbon dioxide reduction, selective organic transformations and disinfection. Through reviewing the important state-of-the-art advances on this topic, it may provide new opportunities for designing and constructing highly effective g-C3N4-based photocatalysts for various applications in photocatalysis and other related fields, such as solar cell, photoelectrocatalysis, electrocatalysis, lithium battery, supercapacitor, fuel cell and separation and purification.

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1,504 Citations

Journal ArticleDOI: 10.1021/ACS.JPCLETT.5B01559
Abstract: The electrochemical reduction of CO2 has gained significant interest recently as it has the potential to trigger a sustainable solar-fuel-based economy. In this Perspective, we highlight several heterogeneous and molecular electrocatalysts for the reduction of CO2 and discuss the reaction pathways through which they form various products. Among those, copper is a unique catalyst as it yields hydrocarbon products, mostly methane, ethylene, and ethanol, with acceptable efficiencies. As a result, substantial effort has been invested to determine the special catalytic properties of copper and to elucidate the mechanism through which hydrocarbons are formed. These mechanistic insights, together with mechanistic insights of CO2 reduction on other metals and molecular complexes, can provide crucial guidelines for the design of future catalyst materials able to efficiently and selectively reduce CO2 to useful products.

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999 Citations

Journal ArticleDOI: 10.1039/C6EE00383D
Xiaoxia Chang1, Tuo Wang1, Jinlong Gong1Institutions (1)
Abstract: Large amounts of anthropogenic CO2 emissions associated with increased fossil fuel consumption have led to global warming and an energy crisis. The photocatalytic reduction of CO2 into solar fuels such as methane or methanol is believed to be one of the best methods to address these two problems. In addition to light harvesting and charge separation, the adsorption/activation and reduction of CO2 on the surface of heterogeneous catalysts remain a scientifically critical challenge, which greatly limits the overall photoconversion efficiency and selectivity of CO2 reduction. This review describes recent advances in the fundamental understanding of CO2 photoreduction on the surface of heterogeneous catalysts and particularly provides an overview of enhancing the adsorption/activation of CO2 molecules. The reaction mechanism and pathways of CO2 reduction as well as their dependent factors are also analyzed and discussed, which is expected to enable an increase in the overall efficiency of CO2 reduction through minimizing the reaction barriers and controlling the selectivity towards the desired products. The challenges and perspectives of CO2 photoreduction over heterogeneous catalysts are presented as well.

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878 Citations

Journal ArticleDOI: 10.1021/CS4002089
Kazuhiko Maeda1, Kazuhiko Maeda2Institutions (2)
07 Jun 2013-ACS Catalysis
Abstract: Water splitting on illuminated semiconductors has long been studied as a potential means of converting solar energy into chemical energy in the form of H2, a clean and renewable energy carrier. Photocatalytic water splitting through two-step photoexcitation using two different semiconductor powders and a reversible donor/acceptor pair (so-called shuttle redox mediator) is one of the possible forms of artificial photosynthesis. This system was inspired by natural photosynthesis in green plants and is called the “Z-scheme”. The development of Z-scheme water splitting systems has relied on both finding a new semiconductor photocatalyst that efficiently works in the presence of a shuttle redox mediator and creating active sites to promote surface chemical reactions while suppressing backward reactions involving redox mediators. This review article describes the historical development of photocatalytic water splitting systems driven by the Z-scheme principle.

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Topics: Water splitting (62%), Photocatalytic water splitting (60%), Artificial photosynthesis (59%) ... show more

771 Citations

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