Atomically Dispersed Nickel Anchored on a Nitrogen-Doped Carbon/TiO2 Composite for Efficient and Selective Photocatalytic CH4 Oxidation to Oxygenates

Direct photocatalytic oxidation of methane to liquid oxygenated products is a sustainable strategy for methane valorization at room temperature. However, in this reaction, noble metals are generally needed to function as cocatalysts for obtaining adequate activity and selectivity. Here, we report atomically dispersed nickel anchored on a nitrogen-doped carbon/TiO₂ composite (Ni−NC/TiO₂) as a highly active and selective catalyst for photooxidation of CH₄ to C1 oxygenates with O₂ as the only oxidant. Ni−NC/TiO₂ exhibits a yield of C1 oxygenates of 198 μmol for 4 h with a selectivity of 93 %, exceeding that of most reported high-performance photocatalysts. Experimental and theoretical investigations suggest that the single-atom Ni−NC sites not only enhance the transfer of photogenerated electrons from TiO₂ to isolated Ni atoms but also dominantly facilitate the activation of O₂ to form the key intermediate ⋅OOH radicals, which synergistically lead to a substantial enhancement in both activity and selectivity.     

Atomically Dispersed FeN2P2 Motif with High Activity and Stability for Oxygen Reduction Reaction Over the Entire pH Range

The past decade has witnessed the great potential of Fe-based single-atom electrocatalysis in catalyzing oxygen reduction reaction (ORR). However, it remains a grand challenge to substantially improve their intrinsic activity and long-term stability in acidic electrolytes. Herein, we report a facile chemical vapor deposition strategy, by which high-density Fe atoms (3.97 wt%) are coordinated with square-planar para-positioned nitrogen and phosphorus atoms in a hierarchical carbon framework. The as-crafted atomically dispersed Fe catalyst (denoted Fe-SA/PNC) manifests an outstanding activity towards ORR over the entire pH range. Specifically, the half-wave potential of 0.92 V, 0.83 V, and 0.86 V vs. reversible hydrogen electrode (RHE) are attained in alkaline, neutral, and acidic electrolytes, respectively, representing the high performance among reported catalysts to date. Furthermore, after 30,000 durability cycles, the Fe-SA/PNC remains to be stable with no visible performance decay when tested in 0.1 M KOH and 0.5 M H₂SO₄, and only a minor negative shift of 40 mV detected in 0.1 M HClO₄, significantly outperforming commercial Pt/C counterpart. The coordination motif of Fe-SA/PNC is validated by density functional theory (DFT) calculations. This work provides atomic-level insight into improving the activity and stability of non-noble metal ORR catalysts, opening up an avenue to craft the desired single-atom electrocatalysts.     

钼铁钴硫簇合物催化乙炔还原性质的研究

钼铁钴硫簇合物催化乙炔还原性质的研究①南玉明②（大庆石油学院石化系，安达１５１４００）徐吉庆蔡辉（吉林大学化学系，长春１３００２３）关键词簇合物类立方烷结构催化电化学性质在化学模拟生物固氮研究的推动下，人们已合成了上百种Ｍｏ－Ｆｅ－Ｓ簇合物，并研究了...     

Optimizing Electrocatalytic Nitrogen Reduction via Interfacial Electric Field Modulation: Elevating d-Band Center in WS2-WO3 for Enhanced Intermediate Adsorption

Electrocatalytic nitrogen reduction reaction (ENRR) has emerged as a promising approach to synthesizing green ammonia under ambient conditions. Tungsten (W) is one of the most effective ENRR catalysts. In this reaction, the protonation of intermediates is the rate-determining step (RDS). Enhancing the adsorption of intermediates is crucial to increase the protonation of intermediates, which can lead to improved catalytic performance. Herein, we constructed a strong interfacial electric field in WS₂-WO₃ to elevate the d-band center of W, thereby strengthening the adsorption of intermediates. Experimental results demonstrated that this approach led to a significantly improved ENRR performance. Specifically, WS₂-WO₃ exhibited a high NH₃ yield of 62.38 μg h⁻¹ mg_cat⁻¹ and a promoted faraday efficiency (FE) of 24.24 %. Furthermore, in situ characterizations and theoretical calculations showed that the strong interfacial electric field in WS₂-WO₃ upshifted the d-band center of W towards the Fermi level, leading to enhanced adsorption of −NH₂ and −NH intermediates on the catalyst surface. This resulted in a significantly promoted reaction rate of the RDS. Overall, our study offers new insights into the relationship between interfacial electric field and d-band center and provides a promising strategy to enhance the intermediates adsorption during the ENRR process.     

Recent Progress on 2D Transition Metal Compounds-based Electrocatalysts for Efficient Nitrogen Reduction

Ammonia is a commodity chemical with high added value. Electrochemical reduction of nitrogen has great promise for the sustainable synthesis of ammonia in recent years. Because of its rich resources and unique electronic structure and characteristics, 2D transition metal compounds have been used as electrocatalysts for electrochemical reduction of nitrogen for clean and sustainable production of ammonia. This review outlines the latest development in the use of 2D transition metal compounds as high-efficiency electrocatalysts for nitrogen reduction reaction(NRR). First, we introduce the N₂ reduction mechanism, and briefly summarize the performance indicators of the catalyst. Then, we focused on the functionalization of unique 2D materials to design high-performance 2D electrocatalysts in respect of simulation calculation and experimental development. Finally, the current challenges and future opportunities for NRR electrocatalysts are introduced.     

Feasible Tuning of Surface OVs on (001) TiO2 for Superior Photocatalytic Nitrogen Fixation Activity

A feasible tuning method for oxygen vacancies was realized by annealing under 3 atm H₂ with (001)-exposed TiO₂ nanosheets. The colored TiO₂ sample exhibits an excellent N₂ photo-fixation rate owing to the abundant oxygen vacancies (OVs) thus demonstrating that annealing with high pressure H₂ is exceedingly efficient for tuning surface OVs.     

Atomically Dispersed Nickel(I) on an Alloy‐Encapsulated Nitrogen‐Doped Carbon Nanotube Array for High‐Performance Electrochemical CO2 Reduction Reaction

Single‐atom catalysts (SACs) show great promise for electrochemical CO₂ reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single‐atom electrode greatly limit their performance. Herein, we prepared a nickel single‐atom electrode consisting of isolated, high‐density and low‐valent nickel(I) sites anchored on a self‐standing N‐doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon‐fiber paper. The combination of single‐atom nickel(I) sites and self‐standing array structure gives rise to an excellent electrocatalytic CO₂ reduction performance. The introduction of copper tunes the d‐band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single‐nickel‐atom electrode exhibits a specific current density of ?32.87 mA cm^?2 and turnover frequency of 1962 h^?1 at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency.     

Synthesis of Mesoporous Wall‐Structured TiO2 on Reduced Graphene Oxide Nanosheets with High Rate Performance for Lithium‐Ion Batteries

Mesoporous wall‐structured TiO₂ on reduced graphene oxide (RGO) nanosheets were successfully fabricated through a simple hydrothermal process without any surfactants and annealed at 400 °C for 2 h under argon. The obtained mesoporous structured TiO₂–RGO composites had a high surface area (99 0307 m² g^?1) and exhibited excellent electrochemical cycling (a reversible capacity of 260 mAh g^?1 at 1.2 C and 180 mAh g^?1 at 5 C after 400 cycles), demonstrating it to be a promising method for the development of high‐performance Li‐ion batteries.