No abstract

Nitrogen fixation under ambient conditions remains a significant challenge. Here, we report nitrogen fixation by Ru single-atom electrocatalytic reduction at room temperature and pressure. In contrast to Ru nanoparticles, single Ru sites supported on N-doped porous carbon greatly promoted electroreduction of aqueous N 2 selectively to NH 3 , affording an NH 3 formation rate of 3.665 mg NH 3 h À1 mg À1Ru at À0.21 V versus the reversible hydrogen electrode. Importantly, the addition of ZrO 2 was found to significantly suppress the competitive hydrogen evolution reaction. An NH 3 faradic efficiency of about 21% was achieved at a low overpotential (0.17 V), surpassing many other reported catalysts. Experiments combined with density functional theory calculations showed that the Ru sites with oxygen vacancies were major active centers that permitted stabilization of *NNH, destabilization of *H, and enhanced N 2 adsorption. We envision that optimization of ZrO 2 loading could further facilitate electroreduction of N 2 at both high NH 3 synthesis rate and faradic efficiency.

Electrocatalytic nitrogen fixation is considered a promising approach to achieve NH3 production. However, due to the chemical inertness of nitrogen, it is necessary to develop efficient catalysts to facilitate the process of nitrogen reduction. Here, molybdenum carbide nanodots embedded in ultrathin carbon nanosheets (Mo2C/C) are developed to serve as a catalyst candidate for highly efficient and robust N2 fixation through an electrocatalytic nitrogen reduction reaction (NRR). The as‐synthesized Mo2C/C nanosheets show excellent catalytic performance with a high NH3 yield rate (11.3 µg h−1 mg−1 Mo2C) and Faradic efficiency (7.8%) for NRR under ambient conditions. More importantly, the isotopic experiments using 15N2 as a nitrogen source confirm that the synthesized ammonia is derived from the direct supply of nitrogen. This result also demonstrates the possibility of high‐efficiency nitrogen reduction even though accompanied with vigorous hydrogen evolution.

We report the discovery of a dramatically enhanced N electroreduction reaction (NRR) selectivity under ambient conditions via the Li incorporation into poly(N-ethyl-benzene-1,2,4,5-tetracarboxylic diimide) (PEBCD) as a catalyst. The detailed electrochemical evaluation and density functional theory calculations showed that Li association with the O atoms in the PEBCD matrix can retard the HER process and can facilitate the adsorption of N to afford a high potential scope for the NRR process to proceed in the "[O-Li]·N-H" alternating hydrogenation mode. This atomic-scale incorporation strategy provides new insight into the rational design of NRR catalysts with higher selectivity.

The industrial process used to reduce N 2 to NH 3 , typically the Haber-Bosch process, is energy-intensive and highly dependent on fossil fuels, a major source of greenhouse gas emissions causing undesirable climate change. Electrochemical reduction of N 2 to NH 3 using renewable energy is one attractive approach to address this problem. A major challenge for electrochemical nitrogen reduction reaction (NRR) is low catalytic activity, accompanied by ultralow selectivity. Current studies have made some breakthroughs in Faradaic efficiency, with reasonable current density, while remaining far from satisfying the needs of commercial applications. This review discusses current strategies, focusing on the perspectives of catalyst design, cell configuration, electrolyte choice, etc., to tackle the selectivity challenge. In addition, rigorous control experiments to eliminate possible ammonia contamination and standard ammonia detection methods to ensure data accuracy are proposed, providing guidance for the field of NRR studies. , he continued his studies there as a postdoctoral fellow in 2005. Now he is a full professor at the South China University of Technology, China. His interests focus on inorganic membranes, membrane reactor, and energy materials.

Ti 3 C 2 T x MXene, through exposing more edge sites, is demonstrated to be an efficient catalyst for electrochemical nitrogen fixation at an ultralow overpotential under ambient conditions. On the edge plane, the nitrogen is spontaneously absorbed on the middle Ti and overcomes a low energy barrier to be converted into ammonia compared to that on the basal plane with an unfavorable energy barrier. This proposed strategy is readily applicable to other two-dimensional catalysts to optimize the surface properties for efficient electrochemical nitrogen fixation under ambient conditions.

We demonstrate the design and fabrication of novel nanoarchitectures of MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays for supercapacitors. The crystalline metal Mn layers in the MnO(2)/Mn/MnO(2) sandwich-like nanotubes uniquely serve as highly conductive cores to support the redox active two-double MnO(2) shells with a highly electrolytic accessible surface area and provide reliable electrical connections to MnO(2) shells. The maximum specific capacitances of 937 F/g at a scan rate of 5 mV/s by cyclic voltammetry (CV) and 955 F/g at a current density of 1.5 A/g by chronopotentiometry were achieved for the MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays in solution of 1.0 M Na(2)SO(4). The hybrid MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays exhibited an excellent rate capability with a high specific energy of 45 Wh/kg and specific power of 23 kW/kg and excellent long-term cycling stability (less 5% loss of the maximum specific capacitance after 3000 cycles). The high specific capacitance and charge-discharge rates offered by such MnO(2)/Mn/MnO(2) sandwich-like nanotube arrays make them promising candidates for supercapacitor electrodes, combining high-energy densities with high levels of power delivery.

Constructing efficient catalysts for the N2 reduction reaction (NRR) is a major challenge for artificial nitrogen fixation under ambient conditions. Herein, inspired by the principle of “like dissolves like”, it is demonstrated that a member of the nitrogen family, well‐exfoliated few‐layer black phosphorus nanosheets (FL‐BP NSs), can be used as an efficient nonmetallic catalyst for electrochemical nitrogen reduction. The catalyst can achieve a high ammonia yield of 31.37 μg h−1 mg−1cat. under ambient conditions. Density functional theory calculations reveal that the active orbital and electrons of zigzag and diff‐zigzag type edges of FL‐BP NSs enable selective electrocatalysis of N2 to NH3 via an alternating hydrogenation pathway. This work proves the feasibility of using a nonmetallic simple substance as a nitrogen‐fixing catalyst and thus opening a new avenue towards the development of more efficient metal‐free catalysts.