Iron-based catalysts are considered highly promising as non-noble metal catalysts for oxygen electroreduction. However, the optimization of iron-based catalysts is limited by the well-designed carbon support and highefficiency catalytic sites. Furthermore, achieving high production yield on an industrial scale while maintaining high performance would also be highly encouraged. Therefore, a dual-protection-exposure mechanism was employed for a hierarchical porous carbon (HPC) embedded with Fe-N4 sites (Fe-N4/HPC) catalysts, which were prepared through the ionothermal carbonization of Fe/ZnTBrPP@MgCl2 [5, 10, 15, 20-tetrakis (4 '-bromophenyl) porphyrinato iron (FeTBrPP) mixed with ZnTBrPP on MgCl2 & sdot;6H2O template]. Apart from self-protectionexposure of the Fe/ZnTBrPP itself, the hydrated salt template provided a secondary protection and exposure simultaneously. As a result, the Fe-N4/HPC retains more Fe-N4 sites and a larger BET surface, resulting in excellent ORR activity and durability in alkaline (0.922 V vs. RHE). Interestingly, under the conditions of using hydrated magnesium salt as a soft template, the yield rate of the Fe-N4/HPC significantly higher than the product without hydrated salt. Furthermore, the utilization of Fe-N4/HPC as the cathode in a zinc-air battery demonstrated remarkable performance, achieving an high peak power density (94 mW cm-2) and good stability.

Stimuli-responsive coatings can self-repair their own anticorrosion function in response to environmental changes, but they do not exhibit ideal long-term protective effect due to the lack of ability to regulate corrosive media, while this is vital to practical metal protection. Inspired by catalytic oxygen reduction, Cu-N center doped graphene oxide grafted with hollow periodic mesoporous organosilica nanocontainer (MBT@HPMO/Cu-GO) is synthesized via facile adsorption-pyrolysis strategy. Herein, introduced MBT@HPMO/Cu-GO is to simulta-neously endow coatings with corrosive media shielding, active oxygen consumption and stimuli-responsive functions, thus "three birds with one stone". The target catalyst exhibits excellent oxygen depletion perfor-mance (half-wave potential of 0.85 V) and is uniformly dispersed in the coating to construct steric hindrance against corrosive media. This dual effect allows composite coating to maintain the excellent anticorrosion per-formance over 60 days under oxygen environment. In addition, MBT@HPMO/Cu-GO can release inhibitor at corrosion sites in response to environment change when coating is damaged, so as to restore the protective ability of coating, with impedance increased from 2.4 x 107 omega center dot cm2 to 1.5 x 108 omega center dot cm2. Such multifunctional coating exploration overcomes the protective limitation of current self-healing coatings and sheds light on the design of intelligent long-term anticorrosion coatings.

In view of the critical importance of oxygen to corrosion evolution, to starve corrosion via depleting oxygen in coatings is a promising strategy. In this work, a novel nanocatalytic anticorrosion concept is proposed to design new coating with outstanding corrosion resistance. Different from the passive barrier of traditional coatings and self-repair after corrosion of current stimuli-feedback coatings, such coating could spontaneously eliminate internal diffused oxygen and greatly suppress the corrosion process. As a proof of concept, single-atom Fe-N-C electrocatalyst with isolated FeN4 active sites is synthesized by a simple confined carbonization method, exhibiting excellent oxygen reduction performance (E1/2 = 0.902 V). In composite coating, the evenly dispersed Fe-N-C compensates for the coating defects and serves as oxygen scavengers, which could actively adsorb and consume ambient oxygen, thereby preventing oxygen penetration to the metal substrate surface, eliminating the oxygen contribution to corrosion and significantly boosting the anticorrosion performance of epoxy coating. This in-situ mediation for oxygen in coating prevents metal substrate from receiving new supply of oxygen, while imparting active anticorrosion property to the coating.

The stimuli-responsive anticorrosion coatings have drawn great attention as a prospective corrosion protection approach due to their smart self-repairing properties. In contrast to passive protection mechanism based on post-corrosion microenvironmental changes, a unique active protection strategy based on nanocatalytic oxygen depletion is proposed in this work to inhibit the occurrence of corrosion. Porous Fe-N-C catalysts with outstanding oxygen reduction reaction (ORR) activity (half-wave potential of 0.89 V) is firstly synthesized through pre-coordination with organosilane precursor to obtain homogeneously distributed active sites. When this catalyst is introduced into the coating matrix, uniformly distributed Fe-N-C not only compensates the defects but plays a crucial role in adsorption and consumption of diffused oxygen in the coating. Under this dual action, the penetration of corrosive medium, especially oxygen, through coating to metal substrate is greatly suppressed, resulting in effective corrosion inhibition and a significant increase in corrosion resistance of the composite coating compared to pure epoxy coating. This work provides a new perspective and the starting point for the design of high-performance smart coating with active anticorrosion properties. (c) 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Metal-nitrogen-carbon (M-N-C) catalysts obtained from zeolitic imidazolate frameworks (ZIFs) have great potential in the oxygen reduction reaction (ORR). Herein, based on the same three-dimensional (3D) topological structure of ZIF-67 and ZIF-8, ZIF-67 is grown on the ZIF-8 surface by the epitaxial growth method, and ZIF-8 is used as a sacrificial template to obtain a Co-embedded layered porous carbon nanocage (CoPCN) electrocatalyst. Meanwhile, the self-sacrificing template effectively improves the specific surface area of the porous structure and reduces the depletion of active sites. The CoPCN shows a high half-wave potential of 0.885 V and superior stability as well as excellent methanol resistance. Theoretical calculations demonstrate that the Co-N1-C2 sites of CoPCN effectively reduce the energy barrier of ORR. In addition, a zinc-air battery (ZAB) based on the CoPCN exhibits excellent peak power density (90 mW cm-2) and superior cycle performance. This work presents a novel idea in the design of ZIF precursor systems to synthesize efficient ORR catalysts.

Doping graphene to epoxy resins can improve the protective ability of the coating, but the lack of active anticorrosion function greatly limits its application in the field of anticorrosion. Herein, N/S-rich few-layer-graphene (N/S-FLG) was prepared and adopted to endow epoxy coating with dual passive/active corrosion protection. The obtained amphiphilic N/S-FLG is highly dispersed in the epoxy coating, giving rise to the enhanced hosting effect for graphene defects, avoiding the interface corrosion and blocking the penetration of corrosive species. Furthermore, the doping of N and S endows graphene sheets favourable catalytic ability for corrosive oxygen, actively eliminating its contribution to metal corrosion. Under this dual effect, the passive and active anticorrosion properties of epoxy coating are simultaneously enhanced. The coating with 1 wt

Metal corrosion has spread all over all aspects of national economy and life, causing serious economic losses and ecological hazards. Because of its excellent protective effect and universality, coating has become an important choice for metal corrosion protection. Although the conventional coating can realize metal corrosion protection with its shielding effect, the protection performance gradually decreases due to mechanical damage and corrosive species erosion. Based on the actual corrosion reaction process, the concept of nanocatalytic anticorrosion is proposed in this work to realize the long-term protection for metals. Firstly, oxygen reduction catalyst was obtained by confined pyrolysis and added into epoxy resin to prepare a new nanocatalytic anticorrosion coating, and then the protective performance of the coating was studied in detail. The results show that the catalyst adopt a uniform dodecahedral structure with excellent oxygen reduction ability, the half wave potential is 0.85 V. The catalyst added in the coating can spontaneously consume the diffused oxygen in the coating while enhancing the compactness of the coating to block the corrosive medium, reduceing the contribution of the corrosive medium to the corrosion reaction. Therefore, the probability of metal corrosion can be significantly reduced, and the service life of the coating for metal protection has been greatly prolonged.