NH 3 synthesis by the electrocatalytic N 2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method-the Haber-Boschp rocess-that requires high temperature and pressure.W er eport single Mo atoms anchored to nitrogendoped porous carbon as ac ost-effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks,t his catalyst achieves ah igh NH 3 yield rate (34.0 AE 3.6 mg NH 3 h À1 mg cat. À1 )a nd ahigh Faradaic efficiency (14.6 AE 1.6 %) in 0.1m KOHatroom temperature.T hese values are considerably higher compared to previously reported non-precious-metal electrocatalysts. Moreover,t his catalyst displays no obvious current drop during a5 0000 sN RR, and high activity and durability are achieved in 0.1m HCl. The findings provideapromising lead for the design of efficient and robust single-atom non-preciousmetal catalysts for the electrocatalytic NRR.

Electrochemical carbon monoxide reduction is a promising strategy for the production of value-added multicarbon compounds, albeit yielding diverse products with low selectivities and Faradaic efficiencies. Here, copper single atoms anchored to Ti3C2Tx MXene nanosheets are firstly demonstrated as effective and robust catalysts for electrochemical carbon monoxide reduction, achieving an ultrahigh selectivity of 98% for the formation of multicarbon products. Particularly, it exhibits a high Faradaic efficiency of 71% towards ethylene at −0.7 V versus the reversible hydrogen electrode, superior to the previously reported copper-based catalysts. Besides, it shows a stable activity during the 68-h electrolysis. Theoretical simulations reveal that atomically dispersed Cu–O3 sites favor the C–C coupling of carbon monoxide molecules to generate the key *CO-CHO species, and then induce the decreased free energy barrier of the potential-determining step, thus accounting for the high activity and selectivity of copper single atoms for carbon monoxide reduction.

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Splitting hydrazine into H2 and N2 by electro-catalyzing hydrogen evolution and hydrazine oxidation reactions is promising for replacing fossil energy with H2. However, current hydrazine splitting is achieved using external powers to drive the two reactions, which is inapplicable to outdoor use. Here, Fe-doped CoS2 nanosheets are developed as a bifunctional electrocatalyst for the two reactions, by which direct hydrazine fuel cells and overall-hydrazine-splitting units are realized and integrated to form a self-powered H2 production system. Without external powers, this system employs hydrazine bifunctionally as the fuel of direct hydrazine fuel cell and the splitting target, namely a sole consumable, and exhibits an H2 evolution rate of 9.95 mmol h−1, a 98% Faradaic efficiency and a 20-h stability, all comparable to the best reported for self-powered water splitting. These performances are due to that Fe doping decreases the free-energy changes of H adsorption and adsorbed NH2NH2 dehydrogenation on CoS2.

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It is a major challenge to develop the low-temperature catalysts (LTC, <250 • C) with excellent efficiency and stability for selective catalytic reduction (SCR) of NO x by NH 3 from stationary sources. Mn-based LTC have been widely investigated due to its various valence states and excellent redox performance, while the poisoning by H 2 O or/and SO 2 is one of the severe weaknesses. This paper reviews the latest research progress on Mn-based catalysts that are expected to break through the resistance, such as modified MnO x -CeO 2 , multi-metal oxides with special crystal or/and shape structures, modified TiO 2 supporter, and novel carbon supporter (ACF, CNTs, GE), etc. The SCR mechanisms and promoting effects of redox cycle are described in detail. The reaction kinetics will be a benefit for the quantitative study of Eley-Rideal (ER) and Langmuir-Hinshelwood (LH) mechanisms. This paper also introduces the applications of quantum-chemical calculation using density functional theory to analyze the physic-chemical properties, explicates the reaction and poisoning mechanisms, and directs the design of functional catalysts on molecule levels. The intensive study of H 2 O/SO 2 inhibition effects is by means of the combination analysis of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT), and the amplification of tolerance mechanisms will be helpful to design an excellent SCR catalyst.