Chinese Journal of Catalysis最新文献

Tuning oxygen vacancy (V_O) in metal oxides catalysts that efficiently activates O₂ molecule to promote oxidation reactions remains challenging. Herein, transition metal (M = Mn, Co, and Mo) doping was used to moderate the coordination environment of V_O in La₂FeMO₆ and promote activity for selective oxidation of hydrogen sulfide (H₂S). Various techniques reveal that the introduction of Mn and Co forms the homogeneous double perovskite phase, which results in the formation of asymmetric V_O. Although these asymmetric V_O are more difficult to form than symmetric Fe-V_O-Fe due to the shorter bond distance and stronger bond strength of Fe-O, they are more conducive to the dissociation of O₂ molecules. Among them, the formed rich Fe-V_O-Mn sites from the alternate substitution of Mn to Fe boosted the activation of O₂ molecules of Mn-substituted LaFeO₃. Therefore, enhanced catalytic activity and outstanding sulfur selectivity were achieved as a result of promoted oxygen mobility and reducibility. This work provides an attractive strategy for rational design of advanced oxidation catalysts.

In order to reduce energy consumption in water electrolysis, it is of great importance to design active and stable electrocatalysts for hydrogen evolution reaction (HER) in alkaline solution, especially based on earth-abundant metal. Here we integrate carbon nanotubes (CNTs) and Ni-Ni(OH)₂ heterostructure multifunctional components to design a self-supported 3D CNTs-Ni-Ni(OH)₂ catalyst for HER by composite deposition and subsequent in-situ oxidation. In alkaline solution, this designed CNTs-Ni-Ni(OH)₂ catalyst exhibits 0 mV onset overpotential, and overpotentials of 65 mV and 109 mV at 10 and 50 mA/cm² respectively. Electrochemical measurements, characterizations, and simulation results attribute the outstanding performance to the incorporation of CNTs and heterostructure. CNTs induce the formation 3D catalytic surface, enhance electrochemical active surface area, and more importantly weaken the adsorption of H. Moreover, the formation of heterostructure, especially reversible Ni(OH)₂, supplies active sites and adjusts the adsorption strength of H atom to an optimal value. CNTs and heterostructure synergistically facilitate water adsorption, promote water dissociation, and accelerate H₂ desorption. Significantly, integration of multifunctional components supplies a distinct strategy for development of cost-effective electrocatalyst with outstanding performance.

Photosynthesis is a potential strategy to enable endergonic process that usually needs high-temperature in thermochemistry to supply the energy for inert-bond activation and/or strong endothermic reaction. The conversion of CO₂ into value-added C₂-oxygenates is a promising process to realize artificial photosynthesis, but suffers from relatively lower efficiency due to complex multi-electron (≥ 10) transfer processes and sluggish kinetics of C–C coupling. This work proposes an all-new H₂O-promoted strategy for efficient production of C₂ oxygenates from the concurrent activation and subsequent co-conversion of CO₂ with CH₄ under photo-thermal cooperation, in which photocatalytic H₂O-splitting derived active hydrogen species for CO₂ activation, and concomitant active oxygen species for CH₄ activation. A formation rate of as high as 2.05 mmol g⁻¹ h⁻¹ for C₂-oxygenates (CH₃CHO and CH₃CH₂OH) in a selectivity of > 86% has been afforded over SrTiO_x supported CuCo under 200 °C and ultraviolet-visible illumination. It has been revealed that SrTiO_x drives photocatalytic H₂O-splitting under the excitation primary from ultraviolet light, paired Cu^I/Cu⁰ sites promote the formation of *CH_xO intermediate from CO₂, Co sites conduct CH₄-to-*CH₃, and C–C coupling of *CH_xO and *CH₃ on adjacent Cu-Co facilitates the generation of C₂-oxygenates.

Developing metal-organic frameworks (MOF) based catalysts with high activity and chlorine corrosion resistance is of paramount importance for seawater oxidation at large current density. Herein, we report a heterogeneous structure coupling NiFe-MOF nanoparticles with NiS nanosheets onto Ni foam (denoted as the NiFe-MOF@NiS/NF) via the mild strategy involving sulfur-modified corrosion and electrodeposition treatment. The constructed amorphous/crystalline interfaces could not only facilitate the adequate infiltration of electrolyte and release of O₂ bubbles at large current densities, but also significantly improve the charge transfer from NiFe-MOF to NiS and the adsorption/desorption capacity of oxygen intermediates. Intriguingly, during oxygen evolution reaction process, the sulfate film formed by the self-reconstruction could remarkably inhibit the adsorption of Cl^– ions on the catalyst surface in the seawater electrolytes. Benefiting from the robust corrosion resistance, unique amorphous/crystalline interfaces, and the charge redistribution, the well-designed NiFe-MOF@NiS/NF exhibits the low overpotential of 346 and 355 mV under a high current density of 500 mA cm⁻² in alkaline water and seawater electrolytes, respectively. More importantly, the as-fabricated NiFe-MOF@NiS/NF demonstrates prolonged stability and durability, lasting over 600 h at a current density of 100 mA cm⁻² in both electrolytes. This study enriches the understanding of electronic structure modulation and chlorine corrosion resistance in seawater, providing broad prospects for designing advanced MOF-based catalysts.

Piezocatalysis, as an emerging technology, holds the promise for providing sustainable solutions to environmental remediation and energy management through mechanical energy utilization. Metal titanates (MTs) are well-known for their outstanding piezoelectric response, positioning them as the primary candidates for catalysts in this field. Moreover, their eco-friendly and cost-effective attributes have made them the focus of considerable attention among researchers. However, the insufficient piezocatalytic activity continues to constrain the practical application of MTs. Confronted with suboptimal energy conversion efficiency, enhancing the response to mechanical energy and reducing the subsequent conversion losses are pivotal for improving the piezocatalytic performance. This review commences with the classification and introduction of various MTs relevant to the field of piezocatalysis. Subsequently, the main methods for preparing MTs are presented. Particularly, the design strategies of MTs with excellent piezocatalytic properties are discussed from the perspectives of improving piezoelectric properties and regulating carrier transport, including construction of morphotropic phase boundary, strain engineering, Curie point control, external field-induced polarization, oriented crystal growth, co-catalyst loading, carbon modification, and semiconductor heterostructure construction. Finally, comprehensive challenges to the development of piezocatalytic technology are presented to promote the rational design and practical application of piezocatalysts.

Three TCPP porphyrin-based nanosheet photocatalysts with exposed (400), (022), and (020) planes were synthesized using a dissolution-recrystallization method in a mixture of water and tetrahydrofuran (THF), methanol (MeOH), and ethylene glycol (EG). The TCPP photocatalyst with the exposed (400) surface exhibited the highest H₂O₂ production rate of 29.33 mmol L⁻¹ h⁻¹ g⁻¹ from only H₂O and O₂, surpassing the rates observed for ones with exposed (022) and (020) surfaces by factors of 2.7 and 4.1, respectively, and 1.3 times as that of the reported TCPP prepared by a base/acid self-assembling method. This enhancement can be attributed to the strong internal electric field and high carboxyl group content on the (400) surface, which hindered rapid charge recombination and facilitated challenging water oxidation. Hence, successful manipulation of porphyrin exposure to robust IEF planes enhances the photocatalytic activity of the system and provides valuable insights for the design and development of more efficient organic photocatalysts.

The SSZ-13 zeolite, which exhibits typical CHA topology characterized by 8-membered ring (8-MR) channels, has shown potential for catalyzing dimethyl ether (DME) carbonylation. However, current studies have yet to provide a comprehensive analysis of its catalytic mechanisms. In this study, we investigated the mechanism of SSZ-13-catalyzed DME carbonylation and the role of spatial confinement in this reaction. By exploiting the differences in the radii of the metal ions, we selectively replaced Brønsted acid sites (BAS) within specific channels, as confirmed by quantitative acidity analysis. Combining the activity data and the dissociation energies of the reactants on the BAS within different rings, we found that both the main and side reactions of DME carbonylation occurred on the 8-MR BAS of SSZ-13. Furthermore, the exchange of ions of different radii highlighted the confinement effect of the pore space in the SSZ-13 zeolite. Characterization of the deposits in spent catalysts, along with theoretical insights, revealed that the reduced cage space adversely affects the stabilization of side reaction intermediates, which in turn mitigates side reactions and improves the selectivity toward methyl acetate. This study presents an effective approach to modulate the acid site distribution and spatial confinement and provides critical insights into the determinants of the catalytic performance of SSZ-13. These findings offer valuable guidance for the future design and optimization of zeolites, aiming to enhance their efficacy in catalytic applications.

The catalytic behavior of metal nanocatalysts is intrinsically contingent on the diversity of their exposed surfaces, which can be substantially regulated through the phase engineering of metal nanoparticles. In this study, it is demonstrated that the face-centered cubic (fcc) phase Ru with a close-packed (111) surface presents superior catalytic activity towards CO₂ methanation. This behavior is attributed to its enhanced capability toward CO₂ chemisorption derived from its inherently high surface reactivity. Complete exposure of such surfaces was successfully achieved experimentally by the synthesis of icosahedral Ru metal nanoparticles, which exhibited remarkable performance for CO₂ methanation with 5–8 times higher activity than its conventional hexagonal close-packed (hcp) counterpart when supported on inert supports. However, for the joined fcc-Ru nanoparticles in the fresh catalyst, an fcc- to hcp-phase transformation was observed at a relatively high temperature with the in situ characterizations, which resulted in metal agglomeration and led to catalyst deactivation. However, the CO₂ conversion was still much higher than that of the hcp-phase Ru nanocatalysts, as the monodispersed particles could maintain their fcc phase. Our results demonstrate that phase engineering of Ru nanocatalysts is an effective strategy for a catalyst design with improved catalytic performance. However, the phase transformation could represent a latent instability of the catalysts, which should be considered for the further development of robust catalysts.

α-Fe₂O₃ is a promising photoanode that is limited by its high surface charge recombination and slow water oxidation kinetics. In this study, we synthesized a TiO₂ layer on Ti-Fe₂O₃ by annealing Ti-MOFs, followed by ZIF-67 as a co-catalyst, to fabricate a ZIF-67/TiO₂/Ti-Fe₂O₃ photoanode for photoelectrochemical (PEC) water splitting. The systematic experimental and theoretical results revealed that the improvement in performance was due to multiple effects of the MOF-derived TiO₂. This molecule not only passivates the acceptor surface states of Ti-Fe₂O₃, thereby reducing the number of surface recombination centers, but also acts as an electron barrier to promote charge separation in the Ti-Fe₂O₃ bulk. Moreover, MOF-derived TiO₂ can dramatically reduce the energy barrier for the OER of Ti-Fe₂O₃, thus promoting the conversion of the intermediate *OH into *O. The synergistic improvement in the bulk and surface properties effectively enhanced the water oxidation performance of Ti-Fe₂O₃. The ZIF-67/TiO₂/Ti-Fe₂O₃ photoanode exhibits a photocurrent density of up to 4.04 mA cm⁻² at 1.23 V vs. RHE, which is 9.4 times as that of pure Ti-Fe₂O₃, and has long-term stability. Our work provides a feasible strategy for constructing efficient organic-inorganic hybrid photoelectrodes.

The inefficient reduction of Fe³⁺ and activation of H₂O₂ in the Fenton reaction severely limit its application in practical water treatment. In this study, we developed defective NH₂-UiO-66 (d-NU) with coordinated unsaturated metal sites by adjusting the coordination configuration of Zr, creating a solid-liquid interface to facilitate Fe³⁺ reduction and the sustainable generation of •OH from H₂O₂ activation. The d-NU/Fe³⁺/H₂O₂/Vis system demonstrated highly efficient removal of various organic pollutants, with a rapid Fe²⁺ regeneration rate and exceptional stability over ten cycles. The degradation rate constant of d-NU (0.16112 min^–1) was 11 times higher than that of NH₂-UiO-66 (NU) (0.01466 min^–1) without defects. Characterization combined with density functional calculations revealed that defects induced coordination unsaturation of the Zr sites, leading to in situ electron-metal-support interactions between Fe³⁺ and the support via Zr–O–Fe bridges. This accumulation of electrons from the unsaturated Zr sites enabled the adsorption of Fe³⁺ at the solid-liquid interface, promoting the formation of Fe²⁺ across a wide pH range with a reduced energy barrier. This study introduces a promising strategy for accelerating Fe³⁺ reduction in the solid-liquid interfacial Fenton process for the degradation of organic pollutants.