Influence of Carbon Content in Ni-Doped Mo2C Catalysts on CO Hydrogenation to Mixed Alcohol

Achieving efficient almost CO-free hydrogen production from methanol steam reforming on Cu modified α-MoC

Methanol, serving as a hydrogen carrier, is utilized for hydrogen production through steam reforming, a promising technology for on-vehicle hydrogen applications. Despite the impressive performance of noble-metal catalysts in hydrogen generation, the development of highly efficient non-noble-metal heterogeneous catalysts remains a formidable challenge. In our investigation, we systematically controlled the influence of the MoC phase on the dispersion of active copper metal to enhance the catalytic performance of methanol steam reforming (MSR). Within the Cu/MoC catalyst systems, featuring MoC phases including α-MoC1-x and Mo2C phases, alongside MoO2 phases, the Cu/α-MoC catalyst exhibited exceptional catalytic efficacy at 350 °C. It achieved a remarkable hydrogen selectivity of up to 80% and an outstanding CO selectivity of 0. Notably, its hydrogen production rate reached 44.07 mmol gcat-1 h-1, surpassing that of Cu/Mo2C (37.05 mmol gcat-1 h-1), Cu/MoO2 (19.02 mmol gcat-1 h-1), and commercial CuZnAl (38 mmol gcat-1 h-1) catalysts. Additionally, we introduced the concept of the (Cu1-Cun)/α-MoC catalyst, wherein Cu atoms are immobilized on the α-MoC surface, facilitating the coexistence of isolated Cu atoms (Cu1) and subnanometer copper cluster (Cun) species at a high dispersibility. This innovative design capitalizes on the robust interaction between the α-MoC1-x phase and the Cu active center, yielding a substantial augmentation in the catalytic activity.

Recent advances in the routes and catalysts for ethanol synthesis from syngas

Ethanol, as one of the important bulk chemicals, is widely used in modern society. It can be produced by fermentation of sugar, petroleum refining, or conversion of syngas (CO/H₂). Among these approaches, conversion of syngas to ethanol (STE) is the most environmentally friendly and economical process. Although considerable progress has been made in STE conversion, control of CO activation and C-C growth remains a great challenge. This review highlights recent advances in the routes and catalysts employed in STE technology. The catalyst designs and pathway designs are summarized and analysed for the direct and indirect STE routes, respectively. In the direct STE routes (i.e., one-step synthesis of ethanol from syngas), modified catalysts of methanol synthesis, modified catalysts of Fischer-Tropsch synthesis, Mo-based catalysts, noble metal catalysts and multifunctional catalysts are systematically reviewed based on their catalyst designs. Further, in the indirect STE routes (i.e., multi-step processes for ethanol synthesis from syngas via methanol/dimethyl ether as intermediates), carbonylation of methanol/dimethyl ether followed by hydrogenation, and coupling of methanol with CO to form dimethyl oxalate followed by hydrogenation, are outlined according to their pathway designs. The goal of this review is to provide a comprehensive perspective on STE technology and inspire the invention of new catalysts and pathway designs in the near future.

Mo2C/C catalyst as efficient peroxymonosulfate activator for carbamazepine degradation

Compared with generally reported Mo⁴⁺/Mo⁶⁺ redox cycle, the exposed Mo²⁺ active sites of Mo-based materials may have a superior potential to effectively activate PMS. However, Mo²⁺-involved materials as efficient catalysts in sulfate radical-based advanced oxidation processes (SR-AOPs) has rarely been researched. In this work, a spherical Mo₂C-loaded carbon material, Mo₂C/C, was prepared for the first time by hydrothermal-calcination method directly used as peroxymonosulfate (PMS) activator towards carbamazepine (CBZ) degradation. The results showed that the Mo₂C/C could effectively remove nearly 100% CBZ (5 mg·L^-1) in the presence of 0.75 mM PMS within 75 min under the optimal conditions. It was attributed to the reductive Mo²⁺, as active sites, benefits to absorb PMS on the surface to trigger electron transmission, and the defective carbon structures accelerate the activation of PMS. Consequently, the efficient Mo²⁺/Mo⁴⁺/Mo⁶⁺ electron transfer was achieved, resulting in excellent catalysis. A series of reactive species including SO₄^-, OH and ¹O₂ species participated in CBZ oxidation degradation. Derived from the superior stability and reusability of Mo₂C/C, the removal rate of CBZ still maintained above 80% even after five consecutive cycles, which is expected to be applied in the wastewater treatment including pharmaceuticals in the future.

Enhancing the Overall Electrocatalytic Water-Splitting Efficiency of Mo2C Nanoparticles by Forming Hybrids with UiO-66 MOF

For efficient electrocatalytic water-splitting, developing a nonprecious-metal-based stable and highly active material is the most challenging task. In this paper, we have devised a synthesis strategy for a hybrid catalyst composed of molybdenum carbide (Mo₂C) and a Zr-based metal-organic framework (MOF) (UiO-66) via the solvothermal process. Synergistic effects between Mo₂C and UiO-66 lead to a decrease in the hydrogen adsorption energy on the catalysts, and Mo₂C/UiO-66 hybrids offer excellent catalytic activity in an alkaline environment for water-splitting. Particularly, the optimized Mo₂C/UiO-66 hybrid, termed MCU-2 with 50:50 wt % of both components, displayed the best catalytic performance for both hydrogen and oxygen evolution reactions (HER/OER). It offered a small overpotential of 174.1 mV to attain a current density of 10 mA/cm² and a Tafel plot value of 147 mV/dec for HER. It also offered a low overpotential of around 180 mV to attain a current density of 20 mA/cm² and a Tafel plot value of 134 mV/dec for OER. Additionally, the catalyst was stable for over 24 h and ∼1000 cycles with a very minute shift in performance, and the electrolyzer indicates that a potential of ∼1.3 V is required to reach 10 mA/cm² current density. It can be inferred from the results that the Mo₂C/UiO-66 hybrid is a promising candidate as a nonexpensive and active catalyst for overall electrocatalytic water-splitting as the devised catalyst exhibits enhanced kinetics for both OER and HER, a more exposed surface area, faster electron transport, and enhanced diffusion of the electrolyte.