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1.
    
The reduction of carbon dioxide (CO2) into chemical feedstock is drawing increasing attention as a prominent method of recycling atmospheric CO2. Although many studies have been devoted in designing an efficient catalyst for CO2 conversion with noble metals, low selectivity and high energy input still remain major hurdles. One possible solution is to use the combination of an earth‐abundant electrocatalyst with a photoelectrode powered by solar energy. Herein, for the first time, a p‐type silicon nanowire with nitrogen‐doped graphene quantum sheets (N‐GQSs) as heterogeneous electrocatalyst for selective CO production is demonstrated. The photoreduction of CO2 into CO is achieved at a potential of ?1.53 V versus Ag/Ag+, providing 0.15 mA cm?2 of current density, which is 130 mV higher than that of a p‐type Si nanowire decorated with well‐known Cu catalyst. The faradaic efficiency for CO is 95%, demonstrating significantly improved selectivity compared with that of bare planar Si. The density functional theory (DFT) calculations are performed, which suggest that pyridinic N acts as the active site and band alignment can be achieved for N‐GQSs larger than 3 nm. The demonstrated high efficiency of the catalytic system provides new insights for the development of nonprecious, environmentally benign CO2 utilization.  相似文献   

2.
    
Heterostructured catalysts are hybrid materials that contain interfaces between their constituents formed through combinations of multiple solid‐state materials. The presence of multiple constituents institutes a synergistic effect that endows the catalyst with superior performance and appreciable potential in a diverse range of catalytic applications, including electrocatalytic and photocatalytic reduction of carbon dioxide. These promising catalysts can support a feasible method for large‐scale processing of valuable carbonaceous feedstock or fuel generation and alleviation of atmospheric carbon dioxide levels. Such technologies will serve as the much‐needed remedy for the global energy and environmental crisis. A broad spectrum of recently developed heterostructured catalysts pertaining to electrocatalytic and photocatalytic carbon dioxide reduction is evaluated. The insights included are of relevance to refresh fundamentals pertaining to the electron transfer processes leading to carbon dioxide reduction and the mechanistic reduction pathways yielding a possible multitude of carbonaceous products. Detailed discussions provide a rational understanding of how the hybrid and resultant properties from various combinations are useful in enhancing catalytic function. Lastly, the performance profiles of various catalyst structures together with modification strategies employed are of interest to highlight the current challenges to and directions for future catalyst development.  相似文献   

3.
    
A simple, versatile and cheap synthetic route is demonstrated for the preparation of Co3O4 decorated blood powder derived heteroatom doped porous carbon (BDHC). The inorganic hybrid performs well as an advanced bifunctional non‐precious metal electrocatalyst. The hybridization of Co3O4 with the blood‐derived carbon results in improved activities not only towards the oxygen reduction reaction (ORR), but also in the reverse oxygen evolution reaction (OER). An improved ORR activity and a tuned four electron transfer selectivity can be assigned to a synergistic catalytic effect due the intimate contact between Co3O­4 particles and the highly conductive heteroatom doped carbon support, mediated by cobalt‐nitrogen or cobalt‐phosphorous coordination sites. This heterojunction may facilitate the electron transfer by preventing an accumulation of electron density within the Co3O­4 particles. The straight‐forward and cheap synthesis of the highly active and durable electrocatalyst make it a promising candidate for a next‐generation bifunctional electrocatalyst for applications such as reversible fuel cells/electrolyzers or metal air batteries.  相似文献   

4.
    
Electrochemical reduction of nitrate (NO3RR) holds great promise for environmentally friendly ammonia production. Tandem catalysis is a promising strategy for boosting the NO3RR and inhibiting side effects, but it is still challenged by lacking well-designed catalysts to drive this catalytic process. Herein, the study develops the CuCo branched nanowires (CuCo NW) catalyst, which efficiently converts NO3 − to NH3 on Co (111) and Cu (111) crystal facets through a tandem catalysis mechanism. The in situ grown CuCo NW on Cu foam demonstrates a remarkable Faraday efficiency of 90.3% at 1.0 A cm−2 and maintains stable operation for 200 h at 100 and 200 mA cm−2 in a flow reactor. Density functional theory calculations suggest that the initial absorption and subsequent deoxygenation of *NO3 on Co (111) leading to the formation of *NO2, followed by its transfer to Cu (111) and further conversion to *NH3, establish an optimal pathway by managing rate-determining steps on individual surfaces for NO3RR. To showcase the practical application of the catalyst, the study further develops a scaling-up prototype reactor for continuous ammonia production, realizing the gram-level yield rate of 1474.09 mg h−1 and Faraday efficiency of 91.26% at practical-level 20.0 A.  相似文献   

5.
    
Photocatalysis is considered to be a green and environment-friendly technology since it can convert solar energy into other types of chemical energies. Over the past several years, metal-organic frameworks (MOFs)-based photocatalysts have received remarkable research interest due to their unique morphology, high photocatalytic performance, good chemical stability, easy synthesis, and low cost. In this review, the synthetic strategies of developing MOFs-based photocatalysts are first introduced. Second, the recent progress in the fabrication of various types of MOFs composites photocatalysts is summarized. Third, the different applications including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, nitrogen reduction reaction, carbon dioxide reduction reaction as well as photodegradation of organic pollutants of MOFs-based photocatalysts are summed up. Finally, the challenges and some suggestions for the future development of MOFs- and their composites-based photocatalysts are also highlighted. It is expected that this report will help researchers to systematically devise and develop highly efficient photocatalysts based on MOFs and their composites.  相似文献   

6.
    
The recent advances in electrocatalysis for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR) are thoroughly reviewed. This comprehensive review focuses on the single‐atom catalysts (SACs) including Sc, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, W, Bi, Ru, Rh, Pd, Ag, Ir, Pt, and Au with single‐metal sites or dual‐metal sites. The recent development of single‐atom electrocatalysts with novel configurations and compositions is documented. The understanding of the process–structure–property relationships is highlighted. For the SACs, their electrocatalytic performance and stability in fuel cells, zinc–air batteries, electrolyzers, CO2RR, and NRR are summarized. The challenges and perspectives in the emerging field of single‐atom electrocatalysis are discussed.  相似文献   

7.
    
Nitrogen‐doped carbon materials are proposed as promising electrocatalysts for the carbon dioxide reduction reaction (CRR), which is essential for renewable energy conversion and environmental remediation. Unfortunately, the unclear cognition on the CRR active site (or sites) hinders further development of high‐performance electrocatalysts. Herein, a series of 3D nitrogen‐doped graphene nanoribbon networks (N‐GRW) with tunable nitrogen dopants are designed to unravel the site‐dependent CRR activity/selectivity. The N‐GRW catalyst exhibits superior CO2 electrochemical reduction activity, reaching a specific current of 15.4 A gcatalyst?1 with CO Faradaic efficiency of 87.6% at a mild overpotential of 0.49 V. Based on X‐ray photoelectron spectroscopy measurements, it is experimentally demonstrated that the pyridinic N site in N‐GRW serves as the active site for CRR. In addition, the Gibbs free energy calculated by density functional theory further illustrates the pyridinic N as a more favorable site for the CO2 adsorption, *COOH formation, and *CO removal in CO2 reduction.  相似文献   

8.
    
Electrochemical reduction of CO2 (CO2RR) and nitrogen (NRR) constitute alternatives to fossil fuel-based technologies for the production of high-value-added chemicals. Yet their practical application is still hampered by the low energy and Faradaic efficiencies although numerous efforts have been paid to overcome the fatal shortcomings. To date, most studies have focused on designing and developing advanced electrocatalysts, while the understanding of electrolyte, which would significantly influence the reaction microenvironment, are still not enough to provide insight to construct highly active and selective electrochemical systems. Here, a comprehensive review of the different electrolytes participating in the CO2RR and NRR is provided, including acidic, neutral, alkaline, and water-in-salt electrolyte as aqueous electrolytes, as well as organic electrolyte, ionic-liquids electrolyte, and the mixture of the two as non-aqueous electrolytes. Through the discussion of the roles of these various electrolytes, it is aimed to grasp their essential function during the electrochemical process and how these functions can be used as design parameters for improving electrocatalytic performance. Finally, priorities for future studies are suggested to support the in-depth understanding of the electrolyte effects and thus guide efficient selection for next-generation gas-involving electrochemical reactions.  相似文献   

9.
As it is the most important of the greenhouse gases, the utilization and reduction of carbon dioxide have attracted a great attention. As compared to the technological demands for carbon capture and storage (CCS), carbon dioxide reduction is a safe and effective way to convert carbon dioxide to fuel. In this research, two different catalysts, graphene–titania and zeolite–titania, are used to achieve the carbon dioxide reduction. The characteristics of these materials are analyzed by Brunnauer–Emmett–Teller, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible, scanning electron microscope and transmission electron microscopy. Because of the different features of the catalysts, various products can be generated through different pathways. Formic acid and methanol are the final products when graphene is used as the catalyst, but only methanol can be generated when zeolite–titania is used as the catalyst. The reaction mechanisms and pathways are discussed.  相似文献   

10.
As a nontoxic and cost-effective material, copper pastes have attracted great attention in both academia and industry. However, achieving the long-term stability of copper pastes remains challenging due to their susceptibility to oxidation. Therefore, stable copper nanoparticles with a Cu(0)–Cu(I) core–shell structure containing a surface passivation layer of formate ions-involved Cu(I) coordination polymers are developed. Based on the self-reducing nature of the passivation layer, the nanoparticle-based copper pastes can be sintered in <1 min, showing high electrical conductivity (220 000 S cm−1), mechanical flexibility, and long-term stability after sintering. The excellent properties of the developed copper pastes are even comparable with the ones of silver pastes. These stable copper pastes have broad applications in printed electronics (e.g., glucose sensors, RFID tags, and electromagnetic shielding films), showing great potential in the fabrication of flexible printed electronics.  相似文献   

11.
    
The development of earth-abundant oxygen reduction reaction (ORR) catalysts with high catalytic activity and good stability for practical metal-air batteries remains an enormous challenge. Herein, a highly efficient and durable ORR catalyst is reported, which consists of atomically dispersed Co single atoms (Co-SAs) in the form of Co-N4 moieties and small Co nanoparticles (Co-SNPs) co-anchored on nitrogen-doped porous carbon nanocage (Co-SAs/SNPs@NC). Benefiting from the synergistic effect of Co-SAs and Co-SNPs as well as the enhanced anticorrosion capability of the carbon matrix brought by its improved graphitization degree, the resultant Co-SAs/SNPs@NC catalyst exhibits outstanding ORR activity and remarkable stability in alkaline media, outperforming Co-SAs-based catalyst (Co-SAs@NC), and benchmark Pt/C catalyst. Density functional theory calculations reveal that the strong interaction between Co-SNPs and Co-N4 sites can increase the valence state of the active Co atoms in Co-SAs/SNPs@NC and moderate the adsorption free energy of ORR intermediates, thus facilitating the reduction of O2. Moreover, the practical zinc-air battery assembled with Co-SAs/SNPs@NC catalyst demonstrates a maximum power density of 223.5 mW cm–2, a high specific capacity of 742 W h kg–1 at 50 mA cm–2 and a superior cycling stability.  相似文献   

12.
    
Along with reduced graphene oxide (RGO), water soluble Prussian blue nanoparticles (PBNPs, around 6 nm) are synthesized and broadly characterized. These two types of highly stable, low‐cost and chemically compatible nanomaterials are exploited as building ingredients to prepare electrically enhanced and functionally endorsed nanohybrid electrocatalysts, which are further transformed into free‐standing graphene papers. PBNPs doped graphene papers show highly efficient electrocatalysis towards reduction of hydrogen peroxide and can be used alone as flexible chemical sensors for potential applications in detection of hydrogen peroxide or/and other organic peroxides. The as‐prepared PBNPs–RGO papers are further capable of biocompatible accommodation of enzymes for development of free‐standing enzyme based biosensors. In this regard, glucose oxidase is used as an example for electrocatalytic oxidation and detection of glucose. The present work demonstrates a facile and highly reproducible way to construct free‐standing and flexible graphene paper doped with electroactive catalyst. Thanks to high stability, low‐cost and efficient electrocatalytic characteristics, this kind of nanohybrid material has potential to be produced on a large scale, and offers a broad range of possible applications, particularly in the fabrication of flexible sensing devices and as a platform for electrocatalytic energy conversion.  相似文献   

13.
    
Using an inexpensive and eco-friendly wood substrate, herein, a one-step calcination method is developed to deposit Co-Ni binary nanoparticles into aligned wood channels and an effective carbonized wood (CW) electrode (termed as Co/Ni-CW) is fabricated. Well distributed Co-Ni nanoparticles are achieved by the coordination bonds between the hydroxyl groups on wood matrix and soaked metal cations. Subsequently, high-temperature calcination promotes the nucleation of Co-Ni nanoparticles and the formation of CW. With the uniform distribution of Co-Ni nanoparticles and porous wood structure, not only is a high active surface area, but also the electron and mass diffusion pathways are enhanced. Thus, the as-prepared Co/Ni-CW affords the current density of 10 mA cm–2 at low overpotentials of 330 and 157 mV for oxygen and hydrogen evolution, respectively. Remarkably, when the wood-based bifunctional electrocatalyst is used as both the anode and cathode, a low cell voltage of 1.64 V is required to reach the current density of 10 mA cm–2. Compared with most substrates used in bifunctional electrocatalysts, the abundance, low cost, eco-friendliness, and easy operation of wood-based catalysts allow for an active and scalable electrode for water splitting and many other energy storage devices.  相似文献   

14.
    
Widespread deployment of metal–organic frameworks (MOFs) for CO2 capture remains challenging due to the great energy‐penalty associated with their regeneration. To overcome this challenge, a new type of photodynamic carbon capture material synthesized by incorporating Ag nanocrystals with UiO‐66 (Ag/UiO‐66) framework is presented. Upon the irradiation of visible light, Ag nanocrystals within the composites serve as “nanoheaters” to convert photon energy into thermal energy locally. Driven by such light‐induced localized heat (LLH), the adsorbed CO2 within MOFs is remotely released. The CO2 desorption capacity of such Ag/UiO‐66 composites can be readily regulated by control over their Ag contents and the applied light intensity. Up to 90.5% of CO2 desorption is achieved under the investigated conditions. Distinct from the traditional light‐responsive MOFs for gas trigger release, currently developed LLH‐driven CO2 release method not only offers a promising solution to the heat‐insulating nature of MOFs, but also demonstrates a potentially low energy method to remotely regenerate MOF adsorbents given the utilization of naturally abundant visible light as efficient stimulus.  相似文献   

15.
    
Nonmetallic plasmonic heterostructure TiO2‐mesocrystals/WO3?x‐nanowires (TiO2‐MCs/WO3?x‐NWs) are constructed by coupling mesoporous crystal TiO2 and plasmonic WO3?x through a solvothermal procedure. The continuous photoelectron injection from TiO2 stabilizes the free carrier density and leads to strong surface plasmon resonance (SPR) of WO3?x, resulting in strong light absorption in the visible and near‐infrared region. Photocatalytic hydrogen generation of TiO2‐MCs/WO3?x‐NWs is attributed to plasmonic hot electrons excited on WO3?x‐NWs under visible light irradiation. However, utilization of injected photoelectrons on WO3?x‐NWs has low efficiency for hydrogen generation and a co‐catalyst (Pt) is necessary. TiO2‐MCs/WO3?x‐NWs are used as co‐catalyst free plasmonic photocatalysts for CO2 reduction, which exhibit much higher activity (16.3 µmol g?1 h?1) and selectivity (83%) than TiO2‐MCs (3.5 µmol g?1 h?1, 42%) and WO3?x‐NWs (8.0 µmol g?1 h?1, 64%) for methane generation under UV–vis light irradiation. A photoluminescence study demonstrates the photoelectron injection from TiO2 to WO3?x, and the nonmetallic SPR of WO3?x plays a great role in the highly selective methane generation during CO2 photoreduction.  相似文献   

16.
    
Adapting the coordination environment to influence the electronic configuration of active sites represents an efficient approach for improving the photocatalytic performance of the CO2 reduction reaction (CO2RR) but how to execute it precisely remains challenging. Herein, heteroatom-substitution in Ni-porphyrin to break the coordination symmetry of Ni center is proposed to be an effective solution. Based on this, two symmetry-breaking Ni-porphyrins, namely Ni(Cl)ON3Por and Ni(Cl)SN3Por , are designed and successfully prepared. By theoretical calculation, it is found that symmetry-breaking efficiently regulates the 3d orbital energy levels of Ni center. Furthermore, experimental and theoretical findings jointly revealed that coordination symmetry-breaking of Ni-porphyrins facilitates the generation of highly reactive NiI species during the catalytic process, effectively stabilizing and reducing the energy barrier of formation of the key *COOH intermediate. As a result, Ni(Cl)ON3Por and Ni(Cl)SN3Por gave CO production rates of 24.7 and 38.8 mmol g−1 h−1 as well as selectivity toward CO of 94.0% and 96.4%, respectively, outperforming that of symmetric NiN4Por (CO production rate of 6.6 mmol g−1 h−1 and selectivity of 82.8%). These findings offer microscopic insights into how to modulate the catalytic activity by precisely tuning the coordination environment of active sites and rational design of competent catalyst for CO2RR photocatalysis.  相似文献   

17.
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18.
Silver nanoparticles (AgNPs), obtained by reduction from AgNO3 solution and stabilized in polyvinyl pyrrolidone (PVP), have been synthesized by γ-ray radiolysis. The application of photoelectrocatalytic (PEC) oxidation in ethylene gas treatment using a TiO2 photocatalyst combined with as-prepared AgNPs on activated carbon fiber (ACF) ([Ag+TiO2]/ACF) as a photoelectrode in a Nafion-based photoelectrocatalytic cell is presented. The effects on the PEC degradation of C2H4 of the preparation parameters of the AgNPs, such as the radiation dose and the amount of PVP added, have been systematically investigated. Emphasis is placed on comparison of the C2H4 decomposition rate constant with [Ag+TiO2/ACF] as a photoelectrode in a photoelectrocatalytic cell with that achieved with [TiO2/ACF]. The factors responsible for the enhancing effect of AgNPs on the PEC activity of the [Ag+TiO2/ACF] photoelectrode are discussed.  相似文献   

19.
    
The vast chemical and structural tunability of metal–organic frameworks (MOFs) are beginning to be harnessed as functional supports for catalytic nanoparticles spanning a range of applications. However, a lack of straightforward methods for producing nanoparticle-encapsulated MOFs as efficient heterogeneous catalysts limits their usage. Herein, a mixed-metal MOF, NiMg-MOF-74, is utilized as a template to disperse small Ni nanoclusters throughout the parent MOF. By exploiting the difference in Ni O and Mg O coordination bond strength, Ni2+ is selectively reduced to form highly dispersed Ni nanoclusters constrained by the parent MOF pore diameter, while Mg2+ remains coordinated in the framework. By varying the ratio of Ni to Mg in the parent MOF, accessible surface area and crystallinity can be tuned upon thermal treatment, influencing CO2 adsorption capacity and hydrogenation selectivity. The resulting Ni nanoclusters prove to be an active catalyst for CO2 methanation and are examined using extended X-ray absorption fine structure and X-ray photoelectron spectroscopy. By preserving a segment of the Mg2+-containing MOF framework, the composite system retains a portion of its CO2 adsorption capacity while continuing to deliver catalytic activity. The approach is thus critical for designing materials that can bridge the gap between carbon capture and CO2 utilization.  相似文献   

20.
    
Electrochemical carbon dioxide reduction reaction (CO2RR) offers a promising way of effectively converting CO2 to value-added chemicals and fuels by utilizing renewable electricity. To date, the electrochemical reduction of CO2 to single-carbon products, especially carbon monoxide and formate, has been well achieved. However, the efficient conversion of CO2 to more valuable multicarbon products (e.g., ethylene, ethanol, n-propanol, and n-butanol) is difficult and still under intense investigation. Here, recent progresses in the electrochemical CO2 reduction to multicarbon products using copper-based catalysts are reviewed. First, the mechanism of CO2RR is briefly described. Then, representative approaches of catalyst engineering are introduced toward the formation of multicarbon products in CO2RR, such as composition, morphology, crystal phase, facet, defect, strain, and surface and interface. Subsequently, key aspects of cell engineering for CO2RR, including electrode, electrolyte, and cell design, are also discussed. Finally, recent advances are summarized and some personal perspectives in this research direction are provided.  相似文献   

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