Search

Binary single‐atom catalysts (BSACs) have demonstrated fascinating activities compared to single atom catalysts (SACs) for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Notably, Fe SACs is one of the most promising ORR electrocatalysts, and further revealing the synergistic effects between Fe and other 3d transition metals (M) for FeM BSACs are very important to enhance bifunctional performance. Herein, density functional theory (DFT) calculations are first adapted to demonstrate the role of various transition metals on the bifunctional activity of Fe sites, and a notable volcano relationship is established through the generally accepted adsorption free energy that ΔG*OH for ORR, and ΔG*O−ΔG*OH for OER, respectively. Further, ten of the atomically dispersed FeM anchored on nitrogen‐carbon support (FeM‐NC) are successfully synthesized with typical atomic dispersion by a facile movable type printing method. The experimental data confirms the bifunctional activity diversity of FeM‐NC between the early‐ and late‐ transition metals, agrees very well with the DFT results. More importantly, the optimal FeCu‐NC shows the expected performance with high ORR and OER activity, thereby, the assembled rechargeable zinc–air battery delivers a high power density of 231 mW cm−2, and an impressive stability that can be stably operated over 300 h. [ABSTRACT FROM AUTHOR]

Single-atom catalysts are of great interest because they can maximize the atom-utilization efficiency and generate unique catalytic properties; however, much attention has been paid to single-site active components, rarely to catalyst promoters. Promoters can significantly affect the activity and selectivity of a catalyst, even at their low concentrations in catalysts. In this work, we designed and synthesized CuO catalysts with atomically dispersed co-promoters of Sn and Zn. When used as the catalyst in the Rochow reaction for the synthesis of dimethyldichlorosilane, this catalyst exhibited much-enhanced activity, selectivity and stability compared with the conventional CuO catalysts with promoters in the form of nanoparticles. Density functional theory calculations demonstrate that single-atomic Sn substitution in the CuO surface can enrich surface Cu vacancies and promote dispersion of Zn to its atomic levels. Sn and Zn single sites as the co-promoters cooperatively generate electronic interaction with the CuO support, which further facilitates the adsorption of the reactant molecules on the surface, thereby leading to the superior catalytic performance. [ABSTRACT FROM AUTHOR]

In this work, single-atom Ag anchored on nitrogen-doped carbon catalysts are designed to investigate the effect of different N -coordination environments on the ECO 2 RR products pathway. The combination of experiments and theory calculations reveal that the Ag-N 4 -C (pyrrolic N) site facilitates the adsorption of CO 2 to produce CO, whereas Ag-N 3 -C (pyridine N) exhibits the highest binding energy (-4.73 eV) to hold *CO intermediates for dimerization, consequently steering the pathway to ethanol (C 2 H 5 OH) formation with a FE of 42% at −0.97 V vs. RHE. [Display omitted] • Ag N C catalysts with controllable N species and content were prepared. • ECO 2 RR products from CO to C 2 H 5 OH can be regulated. • Ag-N-rGO 0.025 M with pyrrolic N promotes the production of CO. • Ag-N-C 0.05 M with pyridine N facilitates a FE C2H5OH of 42 % at −0.97 V RHE. • Experiments and DFT calculations reveal the structure–activity relationship. The rational modulation of the coordination environment of the active center of single-atom catalysts (SACs) is a potential strategy to improve the activity and selectivity of electrocatalytic CO 2 reduction. We developed a series of single-atom Ag-anchored on N -doped carbon catalysts with different N -coordination environments by regulating the carbon source (glucose/graphene oxide, GO). Results demonstrated that the CO 2 -to-CO/C 2 H 5 OH pathway can be converted through reasonable regulation of the content of pyrrolic N and pyridine N. At a highly dominant pyrrolic N content of 40.0 %, the electrocatalyst of Ag-N-rGO 0.025 M facilitates the formation of CO with a Faradaic efficiency (FE) of 69.7 %. By contrast, when the pyridine N content is 70.5 %, the best Ag-N-C 0.05 M catalyst in the H-cell shows an FE of 42 % for C 2 H 5 OH at −0.97 V vs. RHE; moreover, the FE is stable at 40 % within 31 h. Density functional theory calculations further confirm that the pyrrolic N site is conducive to the conversion of CO 2 to intermediate *CO, whereas pyridine N exhibits the highest binding energy (ΔG = -4.73 eV) to hold *CO intermediates for dimerization, consequently steering the pathway to the formation of C 2 H 5 OH. The results of this study provide novel insights into the rational design of carbon-based SACs based on efficient electrochemical CO 2 reduction reaction and the regulation of CO 2 selectivity and activity for C 2 H 5 OH production. [ABSTRACT FROM AUTHOR]

[Display omitted] • A general strategy is developed to prepare ternary single-atom catalysts. • The ternary single-atom catalyst shows high bifunctional activity. • Theatrical calculations provide insights into enhanced bifunctional performance. Synergistic effects have been demonstrated for binary single-atom catalysts (SACs), while it is still challenging to investigate the activity and performance of ternary SACs due to the lack of robust method to synthesize these materials. Herein, we provide a general approach for the preparation of ternary SACs, and the features of single atoms highly dispersed on the support have been identified and verified. As an illustration, trace platinum decorated iron-cobalt ternary single atom catalysts (PtFeCo/NC) possess an obviously enhanced bifunctional activity of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as well as high stability. The density functional theory calculations reveal that the synergistic effects induced by the introduction of Pt enable modulating the adsorption strength of reaction intermediates both on the Fe-N 4 and Co-N 4 sites, thus enhancing the ORR and OER activity, respectively. In addition, the PtFeCo/NC-based Zn-air battery delivers a higher power density than that of commercial Pt/C-RuO 2 , and can be steadily operated over 188 h. [ABSTRACT FROM AUTHOR]