The gradually increased concentration of carbon dioxide (CO2) in the atmosphere has been recognized as the primary culprit for the rise of the global mean temperature. In recent years, development of ...routes for highly efficient conversion of CO2 has received much attention. This Review describes recent progress on the design and synthesis of solid‐state catalysts for the electrochemical reduction of CO2. The significance of this catalytic conversion is presented, followed by the general parameters for CO2 electroreduction and a summary of the reaction apparatus. We also discuss various types of solid catalysts based on their CO2 conversion mechanisms. We summarize the crucial factors (particle size, surface structure, composition, etc.) determining the performance for electroreduction.
CO2 can do: Electroreduction of CO2 is an important CO2 conversion route because of its high environmental compatibility and good combination with other renewable energy sources. Nanostructured materials exhibit outstanding performances for heterogeneous electrocatalytic CO2 reduction. This Review describes recent advances for these nanostructured heterogeneous catalysts.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A facile photoetching approach is described that alleviates the negative effects from bulk defects by confining the oxygen vacancy (Ovac) at the surface of BiVO4 photoanode, by 10‐minute ...photoetching. This strategy could induce enriched Ovac at the surface of BiVO4, which avoids the formation of excessive bulk defects. A mechanism is proposed to explain the enhanced charge separation at the BiVO4 /electrolyte interface, which is supported by density functional theory (DFT) calculations. The optimized BiVO4 with enriched surface Ovac presents the highest photocurrent among undoped BiVO4 photoanodes. Upon loading FeOOH/NiOOH cocatalysts, photoetched BiVO4 photoanode reaches a considerable water oxidation photocurrent of 3.0 mA cm−2 at 0.6 V vs. reversible hydrogen electrode. An unbiased solar‐to‐hydrogen conversion efficiency of 3.5 % is realized by this BiVO4 photoanode and a Si photocathode under 1 sun illumination.
Surface oxygen vacancies play a significant role in BiVO4 photoanodes during the solar water splitting. Photoetching effectively introduce the surface oxygen vacancies on BiVO4 photoanodes, which enhances the charge separation at the BiVO4/electrolyte interface.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Single-atom catalysts (SACs) with atomically dispersed metals have emerged as a new class of heterogeneous catalysts and have attracted considerable interest because they offer 100% metal atom ...utilization and show excellent catalytic behavior compared with traditionally supported nano-particles. However, it is challenging to explore the active sites and catalytic mechanisms of SACs through common characterization methods due to the isolated single atoms. Therefore, employing theoretical calculations to determine the nature of SACs' active sites and the reaction mechanisms is particularly meaningful. This paper describes the nature of SACs by summarizing the diverse applications and properties of SACs, which starts from computational simulation on a couple of important applications of SACs. Then the distinctive and fundamental properties of SACs are discussed. At last, the challenges and future perspectives of computational calculations for SACs are outlined.
Schematic diagram of theoretical models and applications of single atom catalysts. A review on the theoretical models, intrinsic properties, and the related application of SACs.
Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and efforts have been made to improve its catalytic performance. However, unlike ...Pt‐based catalysts, the nature of the active site and surface structure of the supported vanadium catalysts under reductive reaction conditions still remain elusive. This paper describes the surface structure and the important role of surface‐bound hydroxyl groups on VOx / γ‐Al2O3 catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations. It is shown that hydroxyl groups on the VOx /Al2O3 catalyst (V−OH) are produced under H2 pre‐reduction, and the catalytic performance for PDH is closely connected to the concentration of V−OH species on the catalyst. The hydroxyl groups are found to improve the catalyst that leads to better stability by suppressing the coke deposition.
Lending support: The effect of surface hydroxyl groups, on supported vanadium catalysts, on the activity of propane dehydrogenation is studied. Although surface OH groups slightly suppress its dehydrogenation activity, the catalyst stability is increased. DFT calculations confirm that the existence of OH groups block the exposed V3+, on which there is a strong tendency to form coke.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
It is of great significance to reveal the detailed mechanism of neighboring effects between monomers, as they could not only affect the intermediate bonding but also change the reaction pathway. This ...paper describes the electronic effect between neighboring Zn/Co monomers effectively promoting CO2 electroreduction to CO. Zn and Co atoms coordinated on N doped carbon (ZnCoNC) show a CO faradaic efficiency of 93.2 % at −0.5 V versus RHE during a 30‐hours test. Extended X‐ray absorption fine structure measurements (EXAFS) indicated no direct metal–metal bonding and X‐ray absorption near‐edge structure (XANES) showed the electronic effect between Zn/Co monomers. In situ attenuated total reflection‐infrared spectroscopy (ATR‐IR) and density functional theory (DFT) calculations further revealed that the electronic effect between Zn/Co enhanced the *COOH intermediate bonding on Zn sites and thus promoted CO production. This work could act as a promising way to reveal the mechanism of neighboring monomers and to influence catalysis.
The electronic effect between neighboring Zn/Co monomers that effectively enhances the *COOH adsorption and thus boosts CO2 electroreduction to CO is described.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The exploration of highly efficient electrocatalysts for both oxygen and hydrogen generation via water splitting is receiving considerable attention in recent decades. Up till now, Pt‐based catalysts ...still exhibit the best hydrogen evolution reaction (HER) performance and Ir/Ru‐based oxides are identified as the benchmark for oxygen evolution reaction (OER). However, the high cost and rarity of these materials extremely hinder their large‐scale applications. This paper describes the construction of the ultrathin defect‐enriched 3D Se‐(NiCo)Sx/(OH)x nanosheets for overall water splitting through a facile Se‐induced hydrothermal treatment. Via Se‐induced fabrication, highly efficient Se‐(NiCo)Sx/(OH)x nanosheets are successfully fabricated through morphology optimization, defect engineering, and electronic structure tailoring. The as‐prepared hybrids exhibit relatively low overpotentials of 155 and 103 mV at the current density of 10 mA cm−2 for OER and HER, respectively. Moreover, an overall water‐splitting device delivers a current density of 10 mA cm−2 for ≈66 h without obvious degradation.
The construction of ultrathin defectenriched Se‐(NiCo)Sx/(OH)x nanosheets through a facile Se‐induced hydrothermal treatment is described. Benefiting from morphological optimization, defect engineering, and tailoring of the electronic structure, Se‐(NiCo)Sx/(OH)x exhibits highly efficient activity and long‐term stability for oxygen evolution, hydrogen evolution, and overall water splitting.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Cu‐based electrocatalysts facilitate CO2 electrochemical reduction (CO2ER) to produce multi‐carbon products. However, the roles of Cu0 and Cu+ and the mechanistic understanding remain elusive. This ...paper describes the controllable construction of Cu0‐Cu+ sites derived from the well‐dispersed cupric oxide particles supported on copper phyllosilicate lamella to enhance CO2ER performance. 20 % Cu/CuSiO3 shows the superior CO2ER performance with 51.8 % C2H4 Faraday efficiency at −1.1 V vs reversible hydrogen electrode during the 6 hour test. In situ attenuated total reflection infrared spectra and density functional theory (DFT) calculations were employed to elucidate the reaction mechanism. The enhancement in CO2ER activity is mainly attributed to the synergism of Cu0‐Cu+ pairs: Cu0 activates CO2 and facilitates the following electron transfers; Cu+ strengthens *CO adsorption to further boost C−C coupling. We provide a strategy to rationally design Cu‐based catalysts with viable valence states to boost CO2ER.
Controllable Cu0‐Cu+ pairs derived from the well‐dispersed cupric oxide supported on copper phyllosilicate lamella can break thermodynamic and kinetic limitations of CO2 reduction reaction and achieve the superior CO2 electroreduction performance.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Artificial photosynthesis can be used to store solar energy and reduce CO2 into fuels to potentially alleviate global warming and the energy crisis. Compared to the generation of gaseous products, it ...remains a great challenge to tune the product distribution of artificial photosynthesis to liquid fuels, such as CH3OH, which are suitable for storage and transport. Herein, we describe the introduction of metallic Cu nanoparticles (NPs) on Cu2O films to change the product distribution from gaseous products on bare Cu2O to predominantly CH3OH by CO2 reduction in aqueous solutions. The specifically designed Cu/Cu2O interfaces balance the binding strengths of H* and CO* intermediates, which play critical roles in CH3OH production. With a TiO2 model photoanode to construct a photoelectrochemical cell, a Cu/Cu2O dark cathode exhibited a Faradaic efficiency of up to 53.6 % for CH3OH production. This work demonstrates the feasibility and mechanism of interface engineering to enhance the CH3OH production from CO2 reduction in aqueous electrolytes.
Metallic copper nanoparticles were deposited on Cu2O films to change the product distribution of CO2 reduction in aqueous solution from the gaseous products generated on bare Cu2O to predominantly methanol. The carefully designed Cu/Cu2O interfaces balance the binding strengths of the H* and CO* intermediates, which enables efficient methanol production.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Copper can efficiently electro‐catalyze carbon dioxide reduction to C2+ products (C2H4, C2H5OH, n‐propanol). However, the correlation between the activity and active sites remains ambiguous, impeding ...further improvements in their performance. The facet effect of copper crystals to promote CO adsorption and C−C coupling and consequently yield a superior selectivity for C2+ products is described. We achieve a high Faradaic efficiency (FE) of 87 % and a large partial current density of 217 mA cm−2 toward C2+ products on Cu(OH)2‐D at only −0.54 V versus the reversible hydrogen electrode in a flow‐cell electrolyzer. With further coupled to a Si solar cell, record‐high solar conversion efficiencies of 4.47 % and 6.4 % are achieved for C2H4 and C2+ products, respectively. This study provides an in‐depth understanding of the selective formation of C2+ products on Cu and paves the way for the practical application of electrocatalytic or solar‐driven CO2 reduction.
The facet effect of copper crystals to promote CO adsorption and C−C coupling and consequently yield a superior selectivity (87 % Faradaic efficiency) for C2+ products is described. Record‐high solar conversion efficiencies of 4.47 % and 6.4 % are achieved for C2H4 and C2+ products, respectively.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A hundred years on, the energy‐intensive Haber–Bosch process continues to turn the N2 in air into fertilizer, nourishing billions of people while causing pollution and greenhouse gas emissions. The ...urgency of mitigating climate change motivates society to progress toward a more sustainable method for fixing N2 that is based on clean energy. Surface oxygen vacancies (surface Ovac) hold great potential for N2 adsorption and activation, but introducing Ovac on the very surface without affecting bulk properties remains a great challenge. Fine tuning of the surface Ovac by atomic layer deposition is described, forming a thin amorphous TiO2 layer on plasmon‐enhanced rutile TiO2/Au nanorods. Surface Ovac in the outer amorphous TiO2 thin layer promote the adsorption and activation of N2, which facilitates N2 reduction to ammonia by excited electrons from ultraviolet‐light‐driven TiO2 and visible‐light‐driven Au surface plasmons. The findings offer a new approach to N2 photofixation under ambient conditions (that is, room temperature and atmospheric pressure).
Surface oxygen vacancies play a promotional role in the outer amorphous TiO2 (a‐TiO2) thin layer during the adsorption and activation of N2. The process facilitates N2 reduction to ammonia by excited electrons derived from UV‐light‐driven rutile TiO2 nanorod arrays and visible‐light‐driven gold surface plasmons.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
