Search Results (21)

The rational design of a bimetallic nanostructure with a phase separation and interface is of great importance to enhance electrocatalytic performance. Herein, PdNi heterostructures with controlled elemental distributions were constructed via a seeded growth strategy. Partially coated Ni islands in the Pd-Ni nanowire and strained Pd branches in the Pd-NiPd nanowires are revealed, respectively. Impressively, Pd-NiPd nanowires with abundant branches exhibit a superior mass current density and cycling stability toward an ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR). The highest mass activities of 8.63 A mg_Pd⁻¹ and 12.53 A mg_Pd⁻¹ for EOR and EGOR, respectively, are realized on the Pd-NiPd nanowires. Theoretical calculations indicate that the Pd (100)-PdNi (111) interface stands out as an active site for enhancing OH adsorption and the decreasing CO bonding interaction. This study not only puts forward a simple method to construct bimetallic nanostructures with desired elemental distributions and interfaces but also demonstrates the significance of interface engineering in regulating the catalytic activity of metallic nanomaterials. Full article

Aromatic volatile organic compounds (VOCs) pose significant environmental and public health risks due to their toxicity, carcinogenicity, and role as precursors of hazardous secondary pollutants. Zeolite-based metal catalysts, with their well-defined microporous structures, tunable acidity, and high thermal stability, have shown promise in the catalytic oxidation of aromatic VOCs. However, the influence of the zeolite microenvironment on supported metal active sites remains insufficiently understood, limiting the rational design of advanced catalysts. This review highlights how microenvironmental parameters—including pore architecture, acid site distribution, framework composition, and surface/interface engineering—can be modulated to enhance adsorption, oxygen activation, and metal–support interactions. Advances in hierarchical porosity, heteroatom substitution, and surface hydrophobicity are discussed. This review provides a framework for the development of next-generation zeolite-based catalysts and offers strategic guidance for advancing microenvironment-controlled catalysis in sustainable environmental remediation. Full article

Methane is the second most prevalent greenhouse gas after carbon dioxide in global climate change, and catalytic oxidation technology is a very effective way to eliminate methane. However, the high reaction temperature of methane catalytic oxidation is an urgent problem that needs to be solved. In this work, a series of MnCo₂O_4.5 catalysts were prepared using carbon spheres as templates, combined with metal ion adsorption and calcination processes. Excitingly, the catalytic oxidation activity of MnCo₂O_4.5 spherical catalyst with irregular nanoparticles on the surface for lean methane (T₉₀ = 395 °C) is higher than that of pure phase Co₃O₄ (T₉₀ = 538 °C) and Mo₃O₄ (T₉₀ = 581 °C) spherical catalysts and even surpasses most precious metal catalysts. The main reasons are as follows: (1) The spherical core with irregular nanoparticle morphology significantly increases the specific surface area, creating abundant active sites; (2) through the optimized distribution of oxygen vacancies, rapid oxygen migration through this structure can quickly enter the catalytic zone; (3) the hierarchical wall structure expands the interface and provides spatial accommodation for the catalytic process. Meanwhile, the structure of the ball wall further expands the reaction interface, providing sufficient space for the occurrence of reactions. Rich and highly active oxygen vacancies are evenly distributed on the surface and inside of the ball. The extraordinary performance of low-temperature methane combustion catalysts has opened a promising new path, which is expected to inject strong impetus into the global energy transition and environmental protection. Full article

Surface and interface engineering play a crucial role in enhancing the CO₂ methanation performance of heterogeneous catalysts. In this study, we present NiO-TiO₂ nanoparticles modified with oxygen vacancy-rich Fe₃O₄ clusters, significantly improving CO₂ methanation performance. The as-prepared catalyst (referred to as NiO@Fe₃O₄) achieves an impressive CH₄ selectivity of 91.2% and a methane production yield of 6400.50 μmol/g at 573 K, an approximately 83% increase compared to unmodified NiO nanoparticles (3154.2 μmol/g). The results of physical characterizations and gas chromatography confirm that the outstanding activity and selectivity of the NiO@Fe₃O₄ catalyst arise from the synergistic interaction between its surface-active sites. Notably, the high concentration of oxygen vacancies within Fe₃O₄ enhances CO₂ activation, while adjacent NiO sites efficiently promote H₂ dissociation. These findings provide valuable insights into the rational design of heterogeneous catalysts, highlighting the advantages of Fe₃O₄ as an efficient promoter over conventional metal oxides for catalytic applications. Additionally, we envision that the obtained results will help to design transition metal-based industry viable catalysts for a diverse range of applications. Full article

Metal–oxide interfaces play a prominent role in heterogeneous catalysis. Tailoring the metal–oxide interfaces effectively enhance the catalytic activities and thermal stability of noble metal catalysts. In this work, polyvinyl alcohol-protected reduction and L-arginine induction methods are adopted to prepare Pd catalysts (Pd/Al₂O₃-xCeO₂) that are selectively decorated by CeO₂, which form core–shell-like structures and generate more Pd-CeO₂ interfacial sites, so that the three-way catalytic activity of Pd/Al₂O₃-xCeO₂ catalysts is obviously significantly enhanced due to more adsorption oxygen at the interface of Pd-CeO₂ and good low-temperature reducibility. At the moment, the Pd/Al₂O₃-xCeO₂ catalysts exhibit excellent thermal stability after being calcined at 900 °C for 5 h, owing to the Pd species being highly redispersed on CeO₂ and part of the Pd species being incorporated into the lattice of CeO₂. This is a major reason for the Pd/Al₂O₃-xCeO₂ catalysts to maintain high catalytic activity after aging at high temperatures. It is concluded that the metal–oxide interfaces and the interaction between Pd NPs and CeO₂ are responsible for the excellent catalytic performance and stability of Pd/Al₂O₃-xCeO₂ catalysts in three-way reactions. Full article

Solid Oxide Electrolysis Cells (SOECs) can electro-reduce carbon dioxide to carbon monoxide, which not only effectively utilizes greenhouse gases, but also converts excess electrical energy into chemical energy. Perovskite-based oxides with exsolved metal nanoparticles are promising cathode materials for direct electrocatalytic reduction of CO₂ through SOECs, and have thus received increasing attention. In this work, we doped Pr_0.7Ba_0.3MnO_3−δ at the B site, and after reduction treatment, metal nanoparticles exsolved and precipitated on the surface of the cathode material, thereby establishing a stable metal–oxide interface structure and significantly improving the electrocatalytic activity of the SOEC cathode materials. Through research, among the Pr_0.7Ba_0.3Mn_1−xNi_xO_3−δ (PBMN_x = 0–1) cathode materials, it has been found that the Pr_0.7Ba_0.3Mn_0.9Ni_0.1O_3−δ (PBMN_0.1) electrode material exhibits greater catalytic activity, with a CO yield of 5.36 mL min⁻¹ cm⁻² and a Faraday current efficiency of ~99%. After 100 h of long-term testing, the current can still remain stable and there is no significant change in performance. Therefore, the design of this interface has increasing potential for development. Full article

The versatility and significance of imines (Schiff bases) make them highly attractive for many industrial applications. This study investigates photocatalytic routes for the one-pot synthesis of Schiff bases using alcohol and an aromatic nitro compound as reagents, rather than the more conventional amine and aldehyde or ketone. Utilizing photoirradiation at 370 nm with TiO₂ loaded with various metals, we demonstrate the exceptional efficiency of the one-pot synthesis of Schiff bases under an inert atmosphere. Notably, the Fe₃O₄@TiO₂ magnetic catalyst offers an excellent option for synthesizing the corresponding imine, achieving a remarkable production rate of 6.8 mmol h⁻¹ during the first 6 h of irradiation with UVA light and reaching over 99% yield after 20 h. This success is attributed to a series of reactions involving the photocatalytic oxidation of benzyl alcohol to benzaldehyde and the simultaneous in situ reduction of nitrobenzene to aniline. The subsequent catalytic condensation of these products, facilitated by the active sites at the TiO₂-metal interface, ultimately yields the desired imine. Additionally, while irradiation in the UVA region alone can photocatalyze the process, incorporating blue light (450 nm) accelerates it significantly. Dual-wavelength irradiation increased the production of the benzaldehyde to 77.9 mmol and more than doubled the Schiff base yield, from 7.5 mmol (with UVA light) to 17 mmol in 3 h of irradiation. Additionally, the reusability of the catalyst under simultaneous 450 nm and 370 nm light exposure significantly enhanced Schiff base production, which rose from 16.9 mmol to 48.9 mmol after adding fresh 0.1 M nitrobenzene for the second use. This highlights the effectiveness of color-coordinated catalysis in advancing sustainable chemistry through two-color photochemistry. The magnetic catalytic system not only demonstrates remarkable performance but also shows excellent reusability, representing a promising alternative for sustainable and efficient chemical transformations. Full article

Catalytic conversion of CO₂ to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO₂ utilization and mitigation of CO₂ emissions. Bare Pt shows low activity for the RWGS reaction due to its low oxophilicity, with few research works having concentrated on the inverse metal oxide/Pt catalyst for the RWGS reaction. In this work, MnO_x was deposited on the Pt surface over a SiO₂ support to prepare the MnO_x/Pt inverse catalyst via a co-impregnation method. Addition of 0.5 wt% Mn to 1 wt% Pt/SiO₂ improved the intrinsic reaction rate and turnover frequency at 400 °C by two and twelve times, respectively. Characterizations indicate that MnO_x partially encapsulates the surface of the Pt particles and the coverage increases with increasing Mn content, which resembles the concept of strong metal–support interaction (SMSI). Although the surface accessible Pt sites are reduced, new MnO_x/Pt interfacial perimeter sites are created, which provide both hydrogenation and C-O activation functionalities synergistically due to the close proximity between Pt and MnO_x at the interface, and therefore improve the activity. Moreover, the stability is also significantly improved due to the coverage of Pt by MnO_x. This work demonstrates a simple method to tune the oxide/metal interfacial sites of inverse Pt-based catalyst for the RWGS reaction. Full article

The metal-oxide interaction is of significance to the construction of active sites for Cu-catalyzed CO₂ hydrogenation to methanol. This study examines the effect of ZnO and ZrO₂ composition on the Cu/ZnO/ZrO₂ catalyst structure and surface properties to further tune the catalytic activity for methanol synthesis. The ZnO/ZrO₂ ratio can impact the CuZn alloy formation from strong Cu-ZnO interactions and the surface basic sites for CO₂ adsorption at the Cu-ZrO₂ interface. The proportional correlation of the CuZn alloy content and CO₂ desorption amount with the space-time yield (STY) of methanol reveals a synergistic interaction between Cu and oxides (ZnO and ZrO₂) that enhances methanol synthesis. The optimized Cu/ZnO/ZrO₂ catalyst exhibits higher STY relative to the traditional Cu/ZnO/Al₂O₃ catalyst. The obtained results presented herein can provide insight into the catalyst design for methanol synthesis from CO₂. Full article

Metal–organic frameworks (MOFs) with special morphologies provide the geometric morphology and composition basis for the construction of platforms with excellent catalytic activity. In this work, cobalt–cerium composite oxide hollow dodecahedrons (Co/Cex-COHDs) with controllable morphology and tunable composition are successfully prepared via a high-temperature pyrolysis strategy using Co/Ce-MOFs as self-sacrificial templates. The construction of the hollow structure can expose a larger surface area to provide abundant active sites and pores to facilitate the diffusion of substances. The formation and optimization of phase interface between Co₃O₄ and CeO₂ regulate the electronic structure of the catalytic site and form a fast channel favorable to electron transport, thereby enhancing the electrocatalytic oxygen evolution activity. Based on the above advantages, the optimized Co/Ce0.2-COHDs obtained an enhanced oxygen evolution reaction (OER) performance. Full article

It has been established that gold, when in nanoparticle (NP) form and in contact with reducible oxides, can promote oxidation reactions under mild conditions. Here, we report results from our exploration of the catalytic oxidation of carbon monoxide using catalysts where Au NPs were combined with thin titanium oxide films deposited on SBA-15 using atomic layer deposition (ALD). Both orders of deposition, with TiO₂ added either before or after Au dispersion, were tested for two titania film thicknesses amounting to about half and full TiO₂ monolayers. The resulting catalysts were characterized using various techniques, mainly electron microscopy and N₂ adsorption–desorption isotherms, and the kinetics of the oxidation of CO with O₂ were followed using infrared absorption spectroscopy. A synergy between the Au and TiO₂ phases as it relates to the bonding and conversion of CO was identified, the tuning of which could be controlled by varying the synthetic parameters. The ALD of TiO₂ films proved to be an effective way to maximize the Au-TiO₂ interface sites, and with that help with the activation of molecular oxygen. Full article

Methanol synthesis from the hydrogenation of carbon dioxide (CO₂) with green H₂ has been proven as a promising method for CO₂ utilization. Among the various catalysts, indium oxide (In₂O₃)-based catalysts received tremendous research interest due to the excellent methanol selectivity with appreciable CO₂ conversion. Herein, the recent experimental and theoretical studies on In₂O₃-based catalysts for thermochemical CO₂ hydrogenation to methanol were systematically reviewed. It can be found that a variety of steps, such as the synthesis method and pretreatment conditions, were taken to promote the formation of oxygen vacancies on the In₂O₃ surface, which can inhibit side reactions to ensure the highly selective conversion of CO₂ into methanol. The catalytic mechanism involving the formate pathway or carboxyl pathway over In₂O₃ was comprehensively explored by kinetic studies, in situ and ex situ characterizations, and density functional theory calculations, mostly demonstrating that the formate pathway was extremely significant for methanol production. Additionally, based on the cognition of the In₂O₃ active site and the reaction path of CO₂ hydrogenation over In₂O₃, strategies were adopted to improve the catalytic performance, including (i) metal doping to enhance the adsorption and dissociation of hydrogen, improve the ability of hydrogen spillover, and form a special metal-In₂O₃ interface, and (ii) hybrid with other metal oxides to improve the dispersion of In₂O₃, enhance CO₂ adsorption capacity, and stabilize the key intermediates. Lastly, some suggestions in future research were proposed to enhance the catalytic activity of In₂O₃-based catalysts for methanol production. The present review is helpful for researchers to have an explicit version of the research status of In₂O₃-based catalysts for CO₂ hydrogenation to methanol and the design direction of next-generation catalysts. Full article

The electrolysis of water to produce hydrogen is an effective method for solving the rapid consumption of fossil fuel resources and the problem of global warming. The key to its success is to design an oxygen evolution reaction (OER) electrocatalyst with efficient conversion and reliable stability. Interface engineering is one of the most effective approaches for adjusting local electronic configurations. Adding other metal elements is also an effective way to enrich active sites and improve catalytic activity. Herein, high-valence iron in a heterogeneous interface of NiFe₂O₄/NiMoO₄ composite was obtained through oxygen plasma to achieve excellent electrocatalytic activity and stability. In particular, 270 mV of overpotential is required to reach a current density of 50 mA cm⁻², and the overpotential required to reach 500 mA cm⁻² is only 309 mV. The electron transfer effect for high-valence iron was determined by X-ray photoelectron spectroscopy (XPS). The fast and irreversible reconstruction and the true active species in the catalytic process were identified by in situ Raman, ex situ XPS, and ex situ transmission electron microscopy (TEM) measurements. This work provides a feasible design guideline to modify electronic structures, promote a metal to an active oxidation state, and thus develop an electrocatalyst with enhanced OER performance. Full article

Oxygen evolution reaction (OER) electrocatalysts are pivotal for sustainable hydrogen production through anion exchange membrane electrolysis. Cost-effective transition metals such as nickel and iron-based oxides (Ni–Fe–O_x) have been recognized as viable catalysts for the oxygen evolution process in alkaline media. In this work, we study the electrochemical characterization and stability of the Ni–Fe–O_x to find the suitability for AEM electrolysis. The results indicate that Ni–Fe–O_x has 5 times higher activity than pure Ni. The Ni–Fe–O_x electrodes exhibit an exceptionally high catalytic activity of 22 mA cm⁻² at 1.55 V vs. RHE, and a Tafel value as low as 97 dec⁻¹, for OER to occur. These findings imply that OER occurs at similar places along the Ni–Fe–O_x interface and that the Ni—Fe₂O₃ contact plays a significant role as the OER active site. Furthermore, it is also worth noting that the presence of metallic Ni allows for fast electron transit within the interface, which is necessary for successful electrocatalysis. Aside from the excellent OER performance, the exfoliated Ni–Fe–O_x demonstrated great stability with almost constant potential after 10 h of electrolysis at a current density of 10 mA cm⁻². This work confirms Ni–Fe–O_x is a promising, highly efficient and cost-effective OER catalyst for AEM electrolysis. Full article

Adsorption and interaction of carbon monoxide (CO) and nitric oxide (NO) molecules on the surface of bare Al-Mo(110) system and on that obtained by its in situ oxidation have been studied in ultra-high vacuum (base pressure: ca. 10⁻⁸ Pa) by means of Auger and X-ray photoelectron spectroscopy (AES, XPS), low energy electron diffraction (LEED), reflection–absorption infrared and thermal desorption spectroscopy (RAIRS, TDS), and by the work function measurements. In order to achieve the Al-Mo(110) alloy the thin aluminum film of a few monolayers thick was in situ deposited onto the Mo(110) crystal and then annealed at 800 K. As a result of Al atoms diffusion into the Mo(110) subsurface region and the chemical reaction, the surface alloy of a hexagonal atomic symmetry corresponding to Al₂Mo alloy is formed. The feature of thus formed surface alloy regarding molecular adsorption is that, unlike the bare Mo(110) and Al(111) substrates, on which both CO and NO dissociate, adsorption on the alloy surface is non-dissociative. Moreover, adsorption of carbon monoxide dramatically changes the state of pre-adsorbed NO molecules, displacing them to higher-coordinated adsorption sites and simultaneously tilting their molecular axis closer to the surface plane. After annealing of this coadsorbed system up to 320 K the (CO + NO → CO₂ + N) reaction takes place resulting in carbon dioxide desorption into the gas phase and nitriding of the substrate. Such an enhancement of catalytic activity of Mo(110) upon alloying with Al is attributed to surface reconstruction resulting in appearance of new adsorption/reaction centers at the Al/Mo interface (steric effect), as well as to the Mo d-band filling upon alloying (electronic effect). Catalytic activity mounts further when the Al-Mo(110) is in situ oxidized. The obtained Al-Mo(110)-O ternary system is a prototype of a metal/oxide model catalysts featuring the metal oxides and the metal/oxide perimeter interfaces as a the most active reaction sites. As such, this type of low-cost metal alloy oxide models precious metal containing catalysts and can be viewed as a potential substitute to them. Full article