The advancement of highly efficient bifunctional electrodes tailored for water electrolysis, specifically targeting the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), is pivotal for sustainable hydrogen production. However, sluggish reaction kinetics and elevated overpotentials pose formidable hurdles. In this study, an innovative strategy is introduced by integrating Fe@ZIF-67 onto self-supporting carbonized rattan stem (CR), leveraging its distinctive through-channel macroporous architecture to bolster catalytic efficacy. The self-supporting CR substrate not only enhances mass transport but also facilitates uniform deposition of ZIF-67, ensuring optimal exposure of active sites. A comparative analysis with carbonized basswood (CW) underscores the superior performance of the macroporous CR substrate in augmenting both OER and HER activities. Notably, the Fe@ZIF-CR self-supported electrode achieves an overpotential of 208 mV at 10 mA cm⁻² for oxygen evolution and 317 mV at 100 mA cm⁻² for hydrogen evolution. Additionally, the self-supporting nature of the CR substrate guarantees long-term stability and mitigates catalyst loss during operation. These findings underscore the synergistic advantages of the macroporous structure and ZIF-67 active sites, offering fresh perspectives on the utilization of biomass-derived carbon materials in sustainable energy technologies.
Improving the efficiency of the anodic oxygen evolution reaction (OER) is important to solve the global energy crisis and greenhouse gas emission problems. In this paper, a preparation method for a MIL-53(Fe)@ZIF-67(Co) composite electrode is proposed. The hierarchical structure formed by the combination of MIL-53(Fe) and ZIF-67(Co) provides a rich channel for the transport of electrons and mass in the OER process. XPS analysis and DFT calculations revealed that Fe electrons in MIL-53(Fe) were transferred to Co in ZIF-67(Co) through O, which confirmed the rapid charge transfer effect of this transport channel. The MIL-53(Fe)@ZIF-67(Co) electrode has significant OER performance. When the current density reaches 10 mA cm−2, the overpotential is only 193 mV. This study inaugurates a new way for the rational design of a multiphase interface and the construction of new MOF channel structures.
The performance of zinc–air batteries (ZABs) is often hindered by the limited activity and sluggish kinetics of bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, a high-performance bifunctional catalyst (FeCo-NC@rGO) was synthesized by anchoring ZIF-derived Co5.47N and CoFe nanoparticles (NPs) onto a reduced graphene oxide (rGO) aerogel, accompanied by in situ growth of carbon nanotubes (CNTs). The M–N–C sites within the carbon matrix provide abundant ORR active centers, while Co5.47N and CoFe NPs impart excellent OER activity. As a result, FeCo-NC@rGO exhibits a high ORR half-wave potential of 0.85 V (vs. RHE) and a low OER overpotential of 400 mV at 10 mA cm−2, outperforming Pt/C (0.82 V) and RuO2 (508 mV), respectively. A liquid ZAB using this catalyst achieves an open-circuit voltage of 1.51 V, a power density of 114.6 mW cm−2, a specific capacity of 838.2 mAh g−1, and stable cycling for 250 h. The solid-state ZAB also demonstrates strong performance with excellent durability. This study provides an effective and scalable strategy for developing advanced bifunctional electrocatalysts for high-performance ZABs.
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