Journal of Catalysis最新文献

Chemical looping H₂O splitting is considered as a promising approach to produce hydrogen thanks to its lower energy consumption and carbon footprint compared with traditional steam reforming. Fe-based oxides have been paid much attention but suffer from inferior H₂ production rate and stability due to insufficient activation for H₂O. Herein, it was found that the introduction of Cr into MgFe spinel oxides (MgFe_xCr_2-xO₄, MFCO) could greatly increase the performance of H₂O splitting driven by CH₄ reduction with the highest peak H₂ production rate of about 4.65 mmol min⁻¹ g⁻¹, H₂ productivity of about 2.88 mmol g⁻¹ and good stability during multiple redox cycles for MFCO-46 (the atomic ratio of Fe and Cr of 2:3), which exceeded most of the state-of-the-art Fe-based oxides. This originated from the Cr doping promoting Fe⁰ nanoparticles exsolution by activating CH₄ and Fe-O_v-Cr species formation which relay catalyzed H₂O splitting and was favorable for the fast recovery of lattice oxygen converted.

Ag is often studied as catalyst for electrochemical CO₂ reduction as it shows high selectivity towards CO and is easily alloyed with Cu to enhance performance using CuAg catalysts. In this study, we investigated the effect of temperature on Ag and CuAg catalysts and compare these with previous results on Au and Cu catalysts. We show that the temperature effect is complicated as it shows an interplay with CO₂ concentration, potential and mass transport. It is therefore crucial to deconvolute these parameters and study the effect of temperature under different conditions. Moreover, we show that alloying Ag with Cu can inhibit some of the deactivation effects observed at high temperatures on pure Cu. CuAg alloys can prevent the dominance of hydrogen evolution at elevated temperatures, although an optimum of C2+ products with temperature is still observed.

Direct conversion of methanol and acetic acid (HAc) into acrylic acid (AA) and methyl acrylate (MA) is remarkably significant for the high-value utilization of coal-based chemicals. However, the previous catalysts, due to their single function or poor synergy between multiple active sites, remain large challenges in direct synthesis of acrylic acid. Herein, we designed a novel catalyst system through coating TiO₂ to sodium superionic conductor (NASICON) substrate for direct synthesis of acrylic acid from methanol and acetic acid. It was revealed that the catalyst with TiO₂ coating showed obviously improved performance. The selectivity of AA+MA highly reached 56.1 % at 380 °C, corresponding to the spatiotemporal yield of 46.5 μmol·g⁻¹·min⁻¹. It was demonstrated that TiO₂ coating catalyzes the oxidative dehydrogenation of methanol to formaldehyde, while NASICON substrate exerts important effects on the aldol condensation of formaldehyde and acetic acid, and their effective synergy promotes the direct synthesis of acrylic acid.

Constructing van der Waals (vdW) heterostructures is one of the effective strategies for developing highly efficient photocatalysts. In this study, we have designed a novel BTe/HfS₂ heterostructure and systematically investigated its electronic properties and photocatalytic performance using first-principles calculations. The dynamic stability and thermodynamic stability of the heterostructure are verified through phonon spectrum simulations and ab initio molecular dynamics (AIMD) simulations, respectively, enhancing the likelihood of experimental synthesis. The bandgap of the BTe/HfS₂ heterostructure is 0.12 eV, and the band edge positions satisfy the overall water splitting requirements for photocatalysts. The charge density difference, work function, Bader charge, and band alignment all confirm that the BTe/HfS₂ heterostructure is a typical direct Z-scheme heterostructure, effectively facilitating the separation of photogenerated charge carriers and exhibiting strong redox capability. The solar-to-hydrogen (STH) efficiency of the BTe/HfS₂ heterostructure reaches as high as 17.32 %. Moreover, the heterostructure exhibits strong light absorption capability, reaching a magnitude of 10⁵. The carrier mobility of the BTe/HfS₂ heterostructure surpasses that of two individual monolayer materials, with the hole mobility in the x-direction reaching an impressive 28357.15 cm²s^-1V^-1. Simultaneously, the Gibbs free energy indicates that the BTe/HfS₂ heterostructure can undergo the hydrogen evolution reaction (HER) with only 0.19 eV of external potential at pH = 0. Moreover, at pH = 7, it can spontaneously convert H₂O into O₂. Therefore, the newly designed BTe/HfS₂ heterostructure offers a new direction for practical applications of photocatalysts.

An efficient and straightforward procedure for the synthesis of HFIP esters-containing 2H-benzopyrans has been established through palladium-catalyzed one-pot cyclization/carbonylation reaction of substituted propargyl ethers with HFIP by using formic acid as the CO precursor. A diverse set of 2H-benzopyrans have been formed with HFIP esters as attractive functional groups in moderate to excellent yields. This protocol features broad substrate scopes and no manipulation of toxic CO gas.