Single atom iron implanted polydopamine-modified hollow leaf-like N-doped carbon catalyst for improving oxygen reduction reaction and zinc-air batteries.

Metal-nitrogen-carbon (MNC) catalysts, especially FeNC catalysts, are considered promising candidates to replace Pt-based catalysts, but FeNC catalysts still present certain challenges in controlled-synthesis and energy device applications. In this paper, through the modification strategy of poly-dopamine (PDA) to maintain 2D leaf morphology to obtain more active sites and further adjust the N content, N-doped porous carbon monatomic iron catalyst (FeSA/NPCs) with rich-nitrogen content was prepared. XPS analysis showed that compared with C-ZIF-Fe, the contents of graphite nitrogen and pyridine nitrogen increased in FeSA/NPCs. The hollow structure with defects and Fe-N4 configuration of Fe single atom show more active sites for the catalyst, and positively promote the diffusion of reactants, oxygen exchange and electron transport, thus changing the reaction kinetics and promoting the improvement of ORR activity. FeSA/NPCs electrocatalyst exhibits good half-wave potential and onset potential at low loading (E1/2 = 0.93 V, Eonset = 1.0 V). In addition, the methanol tolerance, stability and Tafel slope are better than those of commercial Pt/C. Excitingly, the zinc-air cell with FeSA/NPCs as cathode material achieves a power density of 223 mW cm-2 and exhibits a long-term stability higher than 200 h. This work shows that nitrogen-doped porous carbon materials as well as iron monoatoms play important roles in improving electrocatalytic performance.

Oxygen-rich ligands tailored for novel metal-organic gel electrocatalyst to promote two-electron selectivity electrocatalysis.

More extensive attention has been garnered about the H2O2 electroproduction via two-electron oxygen reduction reaction (2e- ORR). Aiming to develop a more active, more selective and more stable catalyst, herein we reported an unconventional raw metal-organic gels (MOGs) toward this process. This pioneering work, by ingeniously designing and altering the precursor ligands, achieving precisely controlling the number of oxygen groups (OGs). By elaborately comparing more than 70 samples, uncovered the significance that OGs could sufficiently promote the selectivity for H2O2 electrochemical synthesis through the two-electron pathway (realizing enhancement more than 20% in this work). The most potential Fe0.1Co0.9 MOG (H6L), performing an onset potential of 0.76 V (low overpotential), a high selectivity up to 93% ranging 0.15 V to 0.65 V (large voltage window) and 2.1 electron transfer number (implying the 2e- process dominate). This study, unlike other oxidation treatment, through the precise regulation of precursors, further confirmed the feasibility of oxygen-containing functional groups (OGs) tailoring strategy, providing a possibility for low-cost and efficient potential candidate of 2e- ORR.