Decoration of NiFe‐LDH Nanodots Endows Lower Fe‐d Band Center of Fe₁‐N‐C Hollow Nanorods as Bifunctional Oxygen Electrocatalysts with Small Overpotential Gap

Abstract

Single‐atom Fe‐N‐C (denoted as Fe1‐N‐C) catalysts exhibit inadequate bifunctional activities to conquer the sluggish oxygen reduction and evolution reaction (ORR/OER), hindering their practical applications in rechargeable Zn‐air batteries (ZABs). Here, by employing Fe1‐N‐C hollow nanorods as ORR‐active support, OER‐active NiFe‐layered double hydroxide (NiFe‐LDH) nanodots are evenly decorated through a spatially confined process to form NiFe‐LDH/Fe1‐N‐C heterostructure hollow nanorods with abundant accessible catalytic sites. The NiFe‐LDH/Fe1‐N‐C heterostructure not only enhances the ORR activity of pristine Fe1‐N‐C but also realizes efficient bifunctional ORR/OER activity in one monolithic catalyst. Theoretical calculations reveal that introducing NiFe‐LDH nanodots results in donation of electrons to the Fe1‐N‐C matrix and thus lowers the Fe‐d band center of the Fe‐N4 sites, dramatically narrowing the energy barriers of the ORR rate‐limiting steps. As a result, NiFe‐LDH/Fe1‐N‐C nanorods deliver remarkable ORR activity with a half‐wave potential of 0.90 V versus reversible hydrogen electrode, surpassing bare Fe1‐N‐C and commercial Pt/C. Impressively, the integrated NiFe‐LDH/Fe1‐N‐C catalysts show outstanding bifunctional performance with a small overpotential gap of only 0.65 V. The liquid‐state ZABs with NiFe‐LDH/Fe1‐N‐C as an air‐cathode catalyst deliver a peak power density of 205 mW cm−2 and long‐term cycling stability of up to 400 h.

Mn-doped Co nanoparticles on wood-derived monolithic carbon for rechargeable zinc–air batteries

“…The Tafel slope reflects the rapidity of catalytic kinetics on materials. 44 The lower Tafel slope of CoMn-N@NCW (85 mV dec −1 ) than those of 20% Pt/C (105 mV dec −1 ) and other contrast samples highlights the fastest kinetics in the ORR (Fig. 4b).…”

Recent advances in the rational design of alkaline OER catalysts: from electronic structures to industrial applications

“…Therefore, adjusting the energy level of E d is powerful to modulate the catalytic activity. Alloying treatment, 26,27 doping metal or non-metal atoms, [28][29][30] fabricating vacancies 31,32 or hetero-interface, [33][34][35] introducing tensile or compressive stresses, 36,37 modifying with organic ligand, 38 etc. provide various approaches for tuning the dband center and then the electrochemical reaction kinetics.…”

Urea with trifunctional effects: an assistant for high exposure of single-atom active sites on 2D nanosheets via structural transformation

“…Zn–air batteries (ZABs) have been considered as a promising energy storage and conversion device owing to their high theoretical energy density, low cost, and environmental friendliness, and are predicted to reduce the reliance on fossil fuels and accelerate the development of green energy. 1–3 Platinum group metal (PGM) catalysts are commonly utilized to speed up the sluggish kinetics of the oxygen reduction reaction (ORR) process, which is critical for ZABs. However, the natural scarcity and unsatisfactory durability of PGM catalysts severely limit their widespread application, necessitating the replacement of PGM catalysts by non-noble metal catalysts.…”