Catalyst Research Articles

Size effects of supported Cu-based catalysts for the electrocatalytic CO2 reduction reaction

From the perspective of the size of Cu species on supported substrates, this review summarizes the size effects of supported Cu-based single atoms, diatoms, clusters and nanoparticles on the catalytic activity and selectivity of the CO2 reduction reaction.

Scalable synthesis of CuSn bimetallic catalyst for selective CO2 electroreduction to CO over a wide potential range.

A scalable, and cost-effective method was employed to prepare self-supported CuSn bimetallic catalyst on carbon paper. The obtained CuSn catalyst demonstrates high faradaic efficiency of CO around or above 90% at a broad potential range from -0.7 to -1.8 V vs. reversible hydrogen electrode, greatly surpassing Cu or Sn counterparts.

Electronic and geometric modulations of catalysts for electrochemical CO2 reduction reaction

Modulations of electronic structures of active sites and geometric structures of catalyst supports play important roles in electrocatalytic activity and selectivity for the carbon dioxide reduction reaction.

Structure-performance correlation on bimetallic catalysts for selective CO2 hydrogenation

The NiRu bimetallic structures act like a “H-atom valve” controlling the H2 spillover effect for highly selective CO2 hydrogenation.

Progress in reaction mechanisms and catalyst development of ceria-based catalysts for low-temperature CO2methanation

We present a detailed review on the mechanistic understanding and catalyst development of CeO2-based CO2methanation catalysts. Current challenges for deeper investigations and future perspectives are presented as well.

Evaluation of hybrid amines and alcohol solvent with ion-exchange resin catalysts for energy-efficient CO2 capture

Cation exchange resin catalysts are a novel approach to accomplish improvement in aqueous monoethanolamine (MEA) regeneration.

From Single Crystal to Single Atom Catalysts: Structural Factors Influencing the Performance of Metal Catalysts for CO2 Electroreduction

With the electrochemical CO2 reduction reaction (CO2RR), CO2 can be used as a feedstock to produce value-added chemicals and fuels while storing renewable energy. For its enormous potential, an extensive research effort has been launched to find the most active electrocatalyst. The reduction of catalyst size has been tested and proven as a key approach to increase the activity of CO2RR while reducing capital cost. However, the catalytic selectivity is not linearly related to the catalyst size due to the influence of many other structural factors. Thus, in-depth knowledge of structure-performance relationships of metal catalysts with different sizes aids in designing efficient electrocatalysts for CO2RR. This Review surveys three decades of research on CO2RR and categorizes various metal catalysts into four size regimes, namely, bulk materials in the form of single crystals, nanoparticles, clusters, and single-atom catalysts. The effects of different structural factors, including crystal facet, coordination environment, metal–support interactions, etc., on the catalysts in each size regime are discussed. Finally, general conclusions are provided with perspectives on future directions for better understanding and further development of active and selective catalysts for CO2RR.

Co‐Dissolved Isostructural Polyoxovanadates to Construct Single‐Atom‐Site Catalysts for Efficient CO2Photoreduction

AbstractWe explored a co‐dissolved strategy to embed mono‐dispersed Pt center into V2O5support via dissolving [PtV9O28]7−into [V10O28]6−aqueous solution. The uniform dispersion of [PtV9O28]7−in [V10O28]6−solution allows [PtV9O28]7−to be surrounded by [V10O28]6−clusters via a freeze‐drying process. The V centers in both [PtV9O28]7−and [V10O28]6−were converted into V2O5via a calcination process to stabilize Pt center. These double separations can effectively prevent the Pt center agglomeration during the high‐temperature conversion process, and achieve 100 % utilization of Pt in [PtV9O28]7−. The resulting Pt‐V2O5single‐atom‐site catalysts exhibit a CH4yield of 247.6 μmol g−1 h−1, 25 times higher than that of Pt nanoparticle on the V2O5support, which was accompanied by the lactic acid photooxidation to form pyruvic acid. Systematical investigations on this unambiguous structure demonstrate an important role of Pt−O atomic pair synergy for highly efficient CO2photoreduction.

Co@C core-shell nanostructures anchored on carbon cloth for activation of peroxymonosulfate to degrade tetracycline

Cobalt-based heterogeneous nanocatalysts have attracted much attention in activating persulfate to rapidly eliminate organic pollutant in water. However, it remains a challenge to realize the easily recovery of these nanocatalysts and reduce the leaching of Co ions. Herein, Co@C core-shell nanostructures are anchored on the surface of carbon cloth (CC). The as-obtained immobilized catalyst of Co@C/CC exhibits an enhanced catalytic activity and lower leaching of Co ions in comparison with the bare Co@C nanocatalyt because of the high electrical conductivity and carrier effect of CC. The Co@C/CC demonstrates efficient catalytic performance in activating peroxymonosulfate (PMS) for tetracycline (TC) degradation. 99% of TC can be quickly degraded by the Co@C/CC/PMS system, and the system has good durability and interference resistance as well as wide pH adaptability from 3 to 10. Scavenger quenching experiments and electron paramagnetic resonance (EPR) shows that the non-free radical pathway (1O2) is dominate contribute to the TC degradation. Finally, density functional theory (DFT) calculations yield CC as the primary attack site in TC, and the possible degradation pathways of TC are inferred. Importantly, the immobilized catalyst of Co@C/CC can achieve fast and simple collection and regeneration. This work provides new ideas for the preparation of efficient catalysts with easily recyclable for rapidly eliminate organic pollutant in water.

Gallium Nitride‐based Materials as Promising Catalysts for CO2 Reduction: A DFT Study on the Effect of CO2 Coverage and the Incorporation of Mg Doping or Substitutional In

AbstractCatalytic CO2 conversion to fuels and chemicals is important for mitigating the climate change and reducing the dependence on fossil resources. In order to achieve this goal on a large industrial level, effective catalysts need to be developed. Among them, gallium nitride (GaN) and related Mg‐doped and In‐alloyed systems have been proven as efficient materials for the reduction of highly stable CO2 molecules. This work presents a density functional theory (DFT) investigation, performing periodic boundary condition (PBC) calculations which allow to employ a more extended surface for a detailed analysis of the CO2 coverage, and the effect of Mg doping and In alloying on the CO2 adsorption and its conversion to CO. The results show the great potential of GaN(100) surfaces to simultaneously bind and strongly activate multiple CO2 molecules, which is a crucial aspect for an efficient CO2 conversion process. Moreover, the presence of Mg‐dopant on the top layer is found to be more beneficial for the CO2 adsorption and activation with respect to both the pristine and In‐alloyed system, and this effect is further improved by the inclusion of a second impurity on the top layer. In line with the previous experimental findings, these calculations support the potential of pristine GaN(100) to catalyze the CO2‐to‐CO reduction. The results presented here offer crucial information for the development of more efficient and selective catalysts for the CO2 reduction.

Surface and Interface Engineering for the Catalysts of Electrocatalytic CO2 Reduction.

The massive use of fossil fuels releases a great amount of CO2 , which substantially contributes to the global warming. For the global goal of putting CO2 emission under control, effective utilization of CO2 is particularly meaningful. Electrocatalytic CO2 reduction reaction (eCO2 RR) has great potential in CO2 utilization, because it can convert CO2 into valuable carbon-containing chemicals and feedstock using renewable electricity. The catalyst design for eCO2 RR is a key challenge to achieving efficient conversion of CO2 to fuels and useful chemicals. For a typical heterogeneous catalyst, surface and interface engineering is an effective approach to enhance reaction activity. Herein, the development and research progress in CO2 catalysts with focus on surface and interface engineering are reviewed. First, the fundaments of eCO2 RR is briefly discussed from the reaction mechanism to performance evaluation methods, introducing the role of the surface and interface engineering of electrocatalyst in eCO2 RR. Then, several routes to optimize the surface and interface of CO2 electrocatalysts, including morphology, dopants, atomic vacancies, grain boundaries, surface modification, etc., are reviewed and representative examples are given. At the end of this review, we share our personal views in future research of eCO2 RR.

Steering Carbon Hybridization State in Carbon-Based Metal-free Catalysts for Selective and Durable CO2 Electroreduction

Steering Carbon Hybridization State in Carbon-Based Metal-free Catalysts for Selective and Durable CO₂ Electroreduction

Promotional Role of Oxygen Vacancy Defects and Cu−Ce Interfacial Sites on the Activity of Cu/CeO2 Catalyst for CO2 Hydrogenation to Methanol

AbstractDevelopment of novel catalyst for CO2 conversion to methanol is still a challenge. A series of Cu/CeO2 catalyst were prepared by changing the synthesis procedure. The Cu/CeO2 catalyst were prepared by co‐precipitation, surfactant‐assisted co‐precipitation, and sol‐gel methods for CO2 hydrogenation to methanol are documented. The performance of these catalysts was evaluated to elucidate the role of catalytic properties. The Cu/CeO2 catalyst synthesized by the sol‐gel (Cu/CeO2−SG) method exhibited superior strong basic site density, Cu dispersion, and oxygen vacancy defects than co‐precipitation method. A correlation between strong basic site density, oxygen vacancies, and methanol space time yield was established. Moreover, the promotional role of Cu−Ce interfacial sites on the reduced Cu4t/CeO2(111) cluster in CO2 adsorption and activation has been reported by the DFT calculation. These experimental and theoretical results provide insights into Cu‐CeO2 interaction and role of metal‐support interactions in the CO2 hydrogenation reaction.

Frontispiece: 2D Catalysts for CO2 Photoreduction: Discussing Structure Efficiency Strategies and Prospects for Scaled Production Based on Current Progress

Frontispiece: 2D Catalysts for CO₂ Photoreduction: Discussing Structure Efficiency Strategies and Prospects for Scaled Production Based on Current Progress

Non-supported bimetallic catalysts of Fe and Co for methane decomposition into H2 and a mixture of graphene nanosheets and carbon nanotubes

Herein, non-supported pure and mixed cobalt and iron oxide catalysts were synthesized from nitrate precursors using a simple, environmentally friendly preparation method in which water was the sole solvent. The prepared catalysts were then used to decompose methane into hydrogen and carbon (graphene nanosheets and carbon nanotubes). The fresh and spent catalysts were characterized by employing X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy-energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM) and N2 adsorption-desorption techniques. In addition, the spent catalysts were subjected to thermo-gravimetric analysis (TGA) in order to measure the quantity of carbon deposits on the spent catalysts. The results indicated that the carbon deposited over these catalysts is a mixture of graphene nanosheets and carbon nanotubes (CNT). The results indicated that the mixed oxide catalysts exhibit higher catalytic activity than the pure oxides and that Fe: Co atomic ratio represents the key factor in the catalytic activity of these mixed oxides. After 420 min under the reaction feed, the 50Fe + 50Co catalyst shows the highest catalytic activity towards methane conversion of about 52.6% compared to 41.6% and 31.8% for 75Fe + 25Co and 25Fe + 75Co catalysts, respectively.

S-Doped NiII-Triazolate Derived Ni–S–C Catalyst for Electrochemical CO2 Reduction to CO

S-Doped Ni^II-Triazolate Derived Ni–S–C Catalyst for Electrochemical CO₂ Reduction to CO

Frontispiece: Metal‐Based Aerogels Catalysts for Electrocatalytic CO2 Reduction

Frontispiece: Metal‐Based Aerogels Catalysts for Electrocatalytic CO₂ Reduction

Y-Doped BaCeO3 Perovskite-Supported Ru Catalysts for COx-Free Hydrogen Production from Ammonia: Effect of Strong Metal–Support Interactions

The development of highly efficient Ru-based catalysts for NH3 decomposition is necessary to enable the utilization of NH3 as a COx-free H2 carrier. Modulation of the interactions between the basic support materials and Ru particles significantly enhances the performance of Ru-based catalysts for NH3 decomposition. In this study, the strong metal–support interaction (SMSI) interface between the BaCeO3 perovskite support and Ru particles was controlled by yttrium (Y) doping in the range of 0–20 mol %. The substitution of Y3+ into Ce4+ sites improved the reducibility of the support for the removal of lattice oxygen atoms, which promoted the formation of the SMSI interface between the mobile oxygen-deficient suboxide supports and Ru particles. The Ru catalysts supported on Y-doped BaCeO3 exhibited superior activity compared to undoped and other representative Ru catalysts. Moreover, the SMSI shell encapsulating the Ru particles improved the stability of the Y-doped Ru catalyst. This comprehensive study demonstrates that the enhancement in catalytic performance is attributable to facilitated N2 desorption, which is the rate-limiting step for NH3 decomposition over Ru-based catalysts, via the formation of the SMSI interface. These research findings show that the control of the SMSI interface is a promising strategy for designing highly active catalysts to be used in NH3 decomposition.

Identifying the surface active sites of FeOx-modified Pt/Nb2O5 catalysts in CO and propane oxidation

A comparative study on FeOx-modified Pt/Nb2O5 catalyzing CO and propane oxidation has been conducted to differentiate the surface active sites demanded for these two important reactions. Pt-Fe/Nb2O5 displays improved activity for CO oxidation but decreased activity for propane oxidation compared to Pt/Nb2O5. Detailed characterizations reveal the alteration of the geometrical and electronic states of Pt species and surface acidity induced upon the addition of FeOx, thus clarifying the divergent catalytic responses in CO and propane oxidation. Pt-FeOx interface sites promotes oxygen activation that is a crucial step in CO oxidation, thereby accelerating the CO oxidation. However, the rate-determining step in propane oxidation is propane activation that requires the synergistic catalysis of acid sites and Pt0, the critical active sites for propane oxidation. The inferior activity of Pt-Fe/Nb2O5 in propane oxidation is explained by the coverage of acid sites and Pt species.

Effect of Preparation Method on the Performance of Cu−Mn−(La)−Zr Catalysts for CO2 Hydrogenation to Methanol

AbstractA series of Cu−Mn−(La)−Zr catalysts with molecular ratios of 6 : 3 : (0.35) : 1 was synthesized by sol‐gel (CMLZ−S), co‐precipitation (CML−CP, CMLZ−CP) and hydrothermal (CMLZ−H) methods, respectively. The effects of the Mn and La on the activity of catalysts were investigated. It was found that the addition of La promoted the formation of the medium basic sites. Mn acted as an electronic promotor that transfer electrons through redox reactions, causing other metals to exhibit different valence states, thus promoting the adsorption and activation of H2 and CO2. At a certain temperature, methanol selectivity decreased in the order of CMLZ−H>CMLZ−S>CMLZ−CP>CMZ−CP. The selectivity of methanol is correlated with the distribution of basic sites. For the CMLZ−H catalyst, the highest percentage of moderate basic sites facilitated the activation of CO2, resulting in the highest selectivity of methanol. The CO2 conversion was correlated with the Cu specific surface area.