Excavating and developing highly efficient and cost‐effective nonnoble metal single‐atom catalysts for electrocatalytic reactions is of paramount significance but still in its infancy. Herein, reported is a general NaCl template‐assisted strategy for rationally designing and preparing a series of isolated transition metal single atoms (Fe/Co/Ni) anchored on honeycomb‐like nitrogen‐doped carbon matrix (M1‐HNC‐T1‐T2, M = Fe/Co/Ni, T1 = 500 °C, T2 = 850 °C). The resulting M1‐HNC‐500‐850 with M‐N4 active sites exhibits superior capability for oxygen reduction reaction (ORR) with the half‐wave potential order of Fe1‐HNC‐500‐850 > Co1‐HNC‐500‐850 > Ni1‐HNC‐500‐850, in which Fe1‐HNC‐500‐850 shows better performance than commercial Pt/C. Density functional theory calculations reveal a choice strategy that the strong p–d‐coupled spatial charge separation results the Fe‐N4 effectively merges active electrons for elevating d‐band activity in a van‐Hove singularity like character. This essentially generalizes an optimal electronic exchange‐and‐transfer (ExT) capability for boosting sluggish alkaline ORR activity. This work not only presents a universal strategy for preparing single‐atom electrocatalyst to accelerate the kinetics of cathodic ORR but also provides an insight into the relationship between the electronic structure and the electrocatalytical activity.
Designing well‐defined nanointerfaces is of prime importance to enhance the activity of nanoelectrocatalysts for different catalytic reactions. However, studies on non‐noble‐metal‐interface electrocatalysts with extremely high activity and superior stability at high current density still remains a great challenge. Herein, a class of Co3O4/Fe0.33Co0.66P interface nanowires is rationally designed for boosting oxygen evolution reaction (OER) catalysis at high current density by partial chemical etching of Co(CO3)0.5(OH)·0.11H2O (Co‐CHH) nanowires with Fe(CN)63−, followed by low‐temperature phosphorization treatment. The resulting Co3O4/Fe0.33Co0.66P interface nanowires exhibit very high OER catalytic performance with an overpotential of only 215 mV at a current density of 50 mA cm−2 and a Tafel slope of 59.8 mV dec−1 in 1.0 m KOH. In particular, Co3O4/Fe0.33Co0.66P exhibits an obvious advantage in enhancing oxygen evolution at high current density by showing an overpotential of merely 291 mV at 800 mA cm−2, much lower than that of RuO2 (446 mV). Co3O4/Fe0.33Co0.66P is remarkably stable for the OER with negligible current loss under overpotentials of 200 and 240 mV for 150 h. Theoretical calculations reveal that Co3O4/Fe0.33Co0.66P is more favorable for the OER since the electrochemical catalytic oxygen evolution barrier is optimally lowered by the active Co‐ and O‐sites from the Co3O4/Fe0.33Co0.66P interface.
In the present work, an enhanced and stable anodic electrochemiluminescence (ECL) was observed from a suspension of boron nitride quantum dots (BNQDs) and Ru(bpy), which had a 400-fold enhancement compared with individual Ru(bpy). Interestingly, different from the previous research on BNQDs as a type of optical probe, BNQDs were demonstrated as an efficient coreactant of Ru(bpy)-based ECL for the first time and confirmed by collecting the ECL spectra. The amino-bearing groups and the electrocatalytic effect of the BNQDs endowed them as potential coreactants for ECL of Ru(bpy), and the possible mechanism of the electrode surface reaction was discussed. Several factors including electrode material, the pH of the buffer solution, and the amount of BNQDs were investigated and also further confirmed the role of the BNQDs in the proposed Ru(bpy)/BNQDs system. On the basis of the quenching effect between the excited state of Ru(bpy) and the oxidation form of DA in the ECL system of Ru(bpy)/BNQDs, the ECL sensing platform for DA was successfully established. The proposed ECL system with the outstanding ECL efficiency may hold great potential in the bioanlysis because of the biocompatibility and good stability of BNQDs.
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