Materials Today Catalysis最新文献

Carbon-based catalyst can effectively crack model waste plastic based on polyolefins under contactless induction heating and yield gaseous and liquid hydrocarbons fractions at mild reaction temperatures. High catalytic performances are reached thanks to the stable catalyst bed temperature arising from the high heating rate of the induction setup. By comparison to indirect Joule heating which required much higher temperatures, contactless direct induction heating allows a compensation of the internal temperature loss during such highly endothermic process through direct heat targeting. The single carbon-based catalyst combined a high and stable activity with an extremely high stability as a function of cycling tests with pure or mixed polymers. By comparison to the acid or metal based catalysts used in plastic cracking, such low cost carbon catalyst avoids deactivation within cycling tests and therefore provides an efficient and cost-effective route for waste plastic recycling and also as chemical storage means for renewable energy.

The design of spinel-oxide-based catalysts with high activity and long-term durability for oxygen evolution reaction (OER) confronts grand challenges that may be well tackled by maneuvering the electronic structure of surface catalytic sites within spinel oxides. Herein, we harness a double exchange interaction (DEI) triggered by the synergistic effects of Schottky junction and oxygen vacancies (V_O) to generate high proportions of octahedrally coordinated Ni³⁺ and Co²⁺ (highly active sites) in the edge-sharing [Ni_xCo_1−XO₆] octahedra. Specifically, Schottky junction is formed between metallic Cu nanowires and semiconducting NiCo₂O₄ via a core-shell structure, and abundant V_O sites are created in NiCo₂O₄ via H₂ thermal treatment. As expected, the Cu@V_O-NiCo₂O₄ electrocatalyst allows a significantly boosted OER performance, with a low overpotential of 214 mV at 10 mA cm^-2 and a small Tafel slope of 64.9 mV dec^-1, which outperforms the state-of-the-art RuO₂ catalyst and most of reported Ni-Co based OER catalysts. Our work provides some inspirations for designing high-performance spinel-oxide-based electrocatalysts towards OER via DEI engineering.

The development of functional materials for catalysis applications is a continuing issue, particularly in aqueous-phase catalysis. The creation of inexpensive catalysts with improved catalytic activity is still difficult. In this study, the hollow structured Cu nanospheres decorated on the reduced graphene oxide sheets (h-CuNS/rGO) nanocomposites were successfully prepared and applied in the catalytic reduction of p-nitrophenol (p-NP) in water using sodium borohydride as the reducing agent to obtain industrially useful p-aminophenol (p-AP) within a short time. The structure and morphology of h-CuNS/rGO were studied in order to get a full knowledge of the mechanism underlying the creation of its distinctive hollow structure. In the reduction of p-NP, the h-CuNS/rGO demonstrated significant catalytic activity and reusability. The catalytic hydrogenation mechanism on the surface of h-CuNS/rGO was shown to exhibit a synergistic effect between the catalytic h-CuNS and the supporting rGO. The hollow structure, abundant oxygen vacancies as well as the supported rGO worked together to enhance the catalytic activity during p-NP reduction. Therefore, this work proposes a strategy for the simple synthesis of nanocatalyst with high catalytic performance, which endows the potential applications including catalysis.

Transition metal carbides are known as efficient catalysts or catalyst supports and two-dimensional carbides (MXenes) offer renewed possibilities to anchor metal atoms and promote catalytic performances. This paper first presents an in-depth study of the elaboration of Pt or Pd-loaded Ti₃C₂T_x MXenes and their unstacking for gas-phase catalysis investigations, along with step-by-step characterization by XRD, XPS, SEM and STEM. In particular, the influence of the MXene preparation method (HF vs. LiF-HCl etchants) on surface structure/composition and metal dispersion/oxidation state is disclosed. Second, the catalytic hydrogenation performances of these materials are reported, and reveal the interest of low-loaded Pt/MXene single-atom catalysts in terms of activity, selectivity and resistance to sintering. They present an unusually high selectivity to 2-butene – without butane formation – in butadiene hydrogenation, a model reaction of applied interest for the petrochemical industry. Moreover, in CO₂ reduction to CO (reverse water-gas shift reaction, relevant to greenhouse-gas valorization), these catalysts exhibit up to 99 % selectivity and a superior Pt-molar activity with respect to oxide-supported references. This work may stimulate the elaboration and investigation of other MXene-based systems for thermal heterogeneous catalysis, which remains rarely addressed on these materials.

The traditional method of urea production is a carbon-emitting, energy-intensive technology that contradicts the concept of carbon neutrality. Fortunately, the use of renewable energy in electrochemical synthesis has shown great potential for producing high-value nitrogen products, making electrocatalytic urea production a promising and sustainable approach. However, the low yield and Faraday efficiency, as well as the unclear mechanism of C-N bond formation, limit its large-scale industrial development. Researchers are seeking higher-performance electrocatalysts. This article discusses in detail the latest progress in the electrochemical synthesis of urea using carbon dioxide and various nitrogen sources, including catalyst design and preparation, as well as the mechanism of C-N coupling reactions. It also provides comprehensive analysis on the challenges and prospects facing urea electro-synthesis. The development of targeted and efficient new catalysts for urea synthesis is anticipated to bring about more sustainable and cost-effective production methods.

Technologies for CO₂ capture and utilization (CCU) are crucial for combating ever-increasing climate change. While the electrochemical conversion of captured CO₂ has flourished in the past few years, CO₂ capturing techniques are relatively mature. Typical capturing media include alkaline and amine solutions, as well as porous nanomaterials. Scaling CCU requires efficient integration of initial capture and subsequent conversion processes into one device, which is typically referred to as an integrated process. This approach has witnessed notable progress in recent years, which motivates this timely and comprehensive review. We first compare the economic aspects of separate and integrated CCU systems. Then, we discuss the separate CCU approaches that have traditionally been employed and expound on the motivations to develop an integrated system. We focus specifically on two integrated CCU approaches – direct electrolysis of capture solutions and the adoption of bifunctional porous electrodes. We also introduce the working mechanism of each approach and the latest developments, along with a comprehensive discussion on remaining challenges. To conclude, we provide an overall evaluation and outlook on advancing this integrated approach for CCU.

Oxygen evolution reaction (OER) is a crucial half-reaction in electrochemical water splitting, and efficient and durable electrocatalysts are required to improve the sluggish OER kinetics. However, the inevitable formation of chemical oxygen species (COSs) in the OER process heavily impacts the reaction pathway and kinetics. Precisely identifying the COSs generated during OER and acknowledging their chemo-reactivity is highly beneficial for understanding the OER mechanism and facilitating the rational design of advanced catalysts. One of the major challenges in probing the COSs is the detection of COSs under working conditions due to the transient nature and relative low coverage. This review summarizes various COSs detected on different OER electrocatalysts, including adsorbed hydroxyl (M-OH*), adsorbed oxygen (M-O*), adsorbed superoxide intermediates (M-OOH* and M-OO^n-*). With these COSs probed, the possible OER mechanisms with the inter-conversion of these COSs are described. Additionally, the detailed in situ techniques for characterizing specific COSs are also introduced. Finally, we discuss remaining challenges in identifying the COSs and provide some perspectives for the design of next-generation OER electrocatalysts. By emphasizing the COSs during OER, we aim to provide vivid images of the OER transformations on the atomic scales and encourage more studies on correlating the atomic pictures of OER pathways with the active sites as well as catalyst structures.

Developing high-performance and cost-effective electrocatalysts for clean and renewable energy conversion process has been proved a promising approach to deal with the global energy and environment issues. Single-atom alloy (SAA) catalyst, with foreign metal atoms atomically dispersed in the surface of a host metal, combines the merits of conventional metal alloys and single-atom catalysts. The maximum atomic utilization of active metal and unique structural and electrical properties of SAA offer great potential in boosting electrocatalytic activity and reducing the cost of manufacture. Meanwhile, the well-defined active sites raise an opportunity to shed the light on structure-activity relationship and further direct the synthesis of high-efficiency electrocatalysts. Herein, we focus on the recent developments of advanced SAA catalysts and discussed the general properties of SAAs. Then the design principle and synthetic methods were summarized. Next, we highlighted the practical applications of SAAs in electrocatalytic energy conversion and chemicals production, including hydrogen evolution reaction, oxygen evolution reaction, CO₂ reduction reaction, N₂ reduction reaction and other representative reactions. Finally, the challenges and future directions of SAAs are presented.