Identification of Cu(111) as Superior Active Sites for Electrocatalytic NO Reduction to NH3 with High Single-Pass Conversion Efficiency.

Opting for NO as an N source in electrocatalytic NH3 synthesis presents an intriguing approach to tackle energy and environmental challenges. However, blindly pursuing high NH3 synthesis rates and Faradaic efficiency (FE) while ignoring the NO conversion ratio could result in environmental problems. Herein, Cu nanosheets with exposed (111) surface is fabricated and exhibit a NO-to-NH3 yield rate of 371.89 µmol cm-2 h-1 (flow cell) and the highest FE of 93.19±1.99 % (H-type cell). The NO conversion ratio is increased to the current highest value of 63.74 % combined with the development of the flow cell. Additionally, Crystal Orbital Hamilton Population (COHP) clearly reveals that the "σ-π* acceptance-donation" is the essence of the interaction between the Cu and NO as also supported by operando attenuated total reflection infrared spectroscopy (ATR-IRAS) in observing the key intermediate of NO- . This work not only achieves a milestone NO conversion ratio for electrocatalytic NO-to-NH3 , but also proposes a new descriptor that utilizes orbital hybridization between molecules and metal centers to accurately identify the real active sites of catalysts.

P-Doped graphene toward enhanced electrocatalytic N2 reduction.

Catalysts for the N2 reduction reaction (NRR) are at the heart of key alternative technology to the Haber-Bosch process for NH3 synthesis, and are expected to optimize the interplay between efficiency, activity and selectivity. Here, we report our recent finding that P-doped graphene shows superior NRR performances in aqueous media at present, with a remarkably large NH3 yield of 32.33 µg h-1 mgcat.-1 and a high faradaic efficiency of 20.82% at -0.65 V vs. reversible hydrogen electrode. The mechanism is clarified by density functional theory calculations.

Highly Selective Electrochemical Reduction of CO2 to Alcohols on an FeP Nanoarray.

Electrochemical reduction of CO2 into various chemicals and fuels provides an attractive pathway for environmental and energy sustainability. It is now shown that a FeP nanoarray on Ti mesh (FeP NA/TM) acts as an efficient 3D catalyst electrode for the CO2 reduction reaction to convert CO2 into alcohols with high selectivity. In 0.5 m KHCO3 , such FeP NA/TM is capable of achieving a high Faradaic efficiency (FE CH 3 OH ) up to 80.2 %, with a total FE CH 3 OH + C 2 H 5 OH of 94.3 % at -0.20 V vs. reversible hydrogen electrode. Density functional theory calculations reveal that the FeP(211) surface significantly promotes the adsorption and reduction of CO2 toward CH3 OH owing to the synergistic effect of two adjacent Fe atoms, and the potential-determining step is the hydrogenation process of *CO.

Dendritic Cu: a high-efficiency electrocatalyst for N2 fixation to NH3 under ambient conditions.

The artificial N2 fixation to NH3 is dominated by the traditional Haber-Bosch process, which consumes large amounts of energy and natural gas with low energy efficiency and large amounts of CO2 emissions. Electrochemical N2 reduction is a promising and environmentally friendly route for artificial N2-to-NH3 fixation under milder conditions. Herein, we report that dendritic Cu acts as a highly active electrocatalyst to catalyze N2 to NH3 fixation under ambient conditions. When tested in 0.1 M HCl, such an electrocatalyst achieves a high faradaic efficiency of 15.12% and a large NH3 yield rate of 25.63 µg h-1 mgcat.-1 at -0.40 V versus a reversible hydrogen electrode. Notably, this catalyst shows high electrochemical stability and excellent selectivity toward NH3 synthesis.

Greatly Improving Electrochemical N2 Reduction over TiO2 Nanoparticles by Iron Doping.

Titanium-based catalysts are needed to achieve electrocatalytic N2 reduction to NH3 with a large NH3 yield and a high Faradaic efficiency (FE). One of the cheapest and most abundant metals on earth, iron, is an effective dopant for greatly improving the nitrogen reduction reaction (NRR) performance of TiO2 nanoparticles in ambient N2 -to-NH3 conversion. In 0.5 m LiClO4 , Fe-doped TiO2 catalyst attains a high FE of 25.6 % and a large NH3 yield of 25.47 µg h-1 mgcat -1 at -0.40 V versus a reversible hydrogen electrode. This performance compares favorably to those of all previously reported titanium- and iron-based NRR electrocatalysts in aqueous media. The catalytic mechanism is further probed with theoretical calculations.

Boron Phosphide Nanoparticles: A Nonmetal Catalyst for High-Selectivity Electrochemical Reduction of CO2 to CH3 OH.

Electrocatalysis has emerged as an attractive way for artificial CO2 fixation to CH3 OH, but the design and development of metal-free electrocatalyst for highly selective CH3 OH formation still remains a key challenge. Here, it is demonstrated that boron phosphide nanoparticles perform highly efficiently as a nonmetal electrocatalyst toward electrochemical reduction of CO2 to CH3 OH with high selectivity. In 0.1 m KHCO3 , this catalyst achieves a high Faradaic efficiency of 92.0% for CH3 OH at -0.5 V versus reversible hydrogen electrode. Density functional theory calculations reveal that B and P synergistically promote the binding and activation of CO2 , and the rate-determining step for the CO2 reduction reaction is dominated by *CO + *OH to *CO + *H2 O process with free energy change of 1.36 eV. In addition, CO and CH2 O products are difficultly generated on BP (111) surface, which is responsible for the high activity and selectivity of the CO2 -to-CH3 OH conversion process.