Zhigang Geng

Abstract The electrochemical reduction of N 2 into NH 3 production under ambient conditions represents an attractive prospect for the fixation of N 2 . However, this process suffers from low yield rate of NH 3 over reported electrocatalysts. In this work, a record‐high activity for N 2 electrochemical reduction over Ru single atoms distributed on nitrogen‐doped carbon (Ru SAs/N‐C) is reported. At −0.2 V versus reversible hydrogen electrode, Ru SAs/N‐C achieves a Faradaic efficiency of 29.6% for NH 3 production with partial current density of −0.13 mA cm −2 . Notably, the yield rate of Ru SAs/N‐C reaches 120.9 , which is one order of magnitude higher than the highest value ever reported. This work not only develops a superior electrocatalyst for NH 3 production, but also provides a guideline for the rational design of highly active and robust single‐atom catalysts.

Abstract As electron transfer to CO 2 is generally considered to be the critical step during the activation of CO 2 , it is important to develop approaches to engineer the electronic properties of catalysts to improve their performance in CO 2 electrochemical reduction. Herein, we developed an efficient strategy to facilitate CO 2 activation by introducing oxygen vacancies into electrocatalysts with electronic‐rich surface. ZnO nanosheets rich in oxygen vacancies exhibited a current density of −16.1 mA cm −2 with a Faradaic efficiency of 83 % for CO production. Based on density functional theory (DFT) calculations, the introduction of oxygen vacancies increased the charge density of ZnO around the valence band maximum, resulting in the enhanced activation of CO 2 . Mechanistic studies further revealed that the enhancement of CO production by introducing oxygen vacancies into ZnO nanosheets originated from the increased binding strength of CO 2 and the eased CO 2 activation.

reduction reaction. Notably, we bridge the understanding between the doping regulation of catalysts and their catalytic activities via focusing on the physicochemical properties of catalysts from the aspects of vacancy concentrations, phase transformation, surface wettability, electrical conductivity, electronic band structure, local charge distribution, tunable adsorption strength, and multiple adsorption configurations. We also discuss the existing challenges and future perspectives in this promising field.

A functional hybrid of reduced graphene oxide (RGO)–Fe3O4 nanoparticles (NPs) has been chemically synthesized with exceptionally high yield and tunable RGO/Fe3O4 ratio. The adsorption behaviors of a series of dyes using this hybrid as the adsorbent are systematically investigated in aqueous solutions through real-time monitoring of the fingerprint spectral changes of the dyes. The results show that, benefiting both from the surface property of RGO and from the magnetic property of Fe3O4, the hybrid possesses quite a good (although unoptimized) and versatile adsorption capacity to the dyes under investigation, and can be easily and rapidly extracted from water by magnetic attraction. Most importantly, it is found that by simply annealing in moderate conditions, this hybrid adsorbent can be easily and efficiently regenerated for reuse with hardly any compromise of the adsorption capacity. Furthermore, the adsorbability of this hybrid shows satisfactory tolerance against the variations in both pH environment and dye concentration. Even when exposed to a multi dye cocktail, the hybrid can work well without suppressing the adsorption capacity for each of the dyes, as compared with that measured separately. The inherent advantages of this nanostructured adsorbent, such as non-compromised adsorption capacity, low cost, easy, rapid extraction and regeneration, good tolerance, multiplex adsorbability, and handy operation, may pave a new, efficient and sustainable way towards highly-efficient dye pollutant removal in Earth's water environments.