Abstract
The electrochemical splitting of water into hydrogen and oxygen is considered one of the most promising approaches to generate clean and sustainable energy. However, the low efficiency of the oxygen evolution reaction (OER) acts as a bottleneck in the water splitting process. Herein, interface engineering heterojunctions between ZIF‐67 and layered double hydroxide (LDH) are designed to enhance the catalytic activity of the OER and the stability of Co‐LDH. The interface is built by the oxygen (O) of Co‐LDH and nitrogen (N) of the 2‐methylimidazole ligand in ZIF‐67, which modulates the local electronic structure of the catalytic active site. Density functional theory calculations demonstrate that the interfacial interaction can enhance the strength of the Co—Oout bond in Co‐LDH, which makes it easier to break the H‐Oout bond and results in a lower free energy change in the potential‐determining step at the heterointerface in the OER process. Therefore, the Co‐LDH@ZIF‐67 exhibits superior OER activity with a low overpotential of 187 mV at a current density of 10 mA cm−2 and long‐term electrochemical stability for more than 50 h. This finding provides a design direction for improving the catalytic activity of OER.
Highlights
The electrochemical splitting of water into hydrogen and oxygen is considered The consumption of fossil fuels and the one of the most promising approaches to generate clean and sustainable energy
The development of an eco-friendly strategy for the production of efficient and sustainable energy could fundamentally settle the (LDH) are designed to enhance the catalytic activity of the oxygen evolution reaction (OER) and the issues related to resource, energy, and stability of Co-layered double hydroxides (LDHs)
Layered double hydroxides (LDHs) have attracted increasing attention owing to their special morphologies, high catalytic activity in OER, and facile synthesis methods.[9,10]
Summary
Interface Engineering of Co-LDH@MOF Heterojunction in Highly Stable and Efficient Oxygen Evolution Reaction. Atomic force microscopy (AFM) results (Figure 2e,f) demonstrated that the average thickness of the Co-LDH nanosheets was 1.5 nm This ultrathin structure generated a significant specific surface area, which led to high catalytic activity for OER. To further investigate the morphology and structure changes of Co-LDH@ZIF-67 after OER process, SEM, TEM, HAADFSTEM-EDS mapping images, XRD, Raman, and XPS were measured, as shown in Figures S15 and S16, Supporting Information. The SEM and TEM images of Co-LDH@ZIF-67 after OER process are shown in Figure S15a,b, Supporting Information, which showed that the morphology of Co-LDH@ZIF-67 still maintained core–shell structure. The XPS results showed that the peak positions of Co, C, N, and O did not change (Figure S16, Supporting Information), confirming the presence of the interface in Co-LDH@ZIF-67 after OER process. Because of the interaction between the well-interfaced Co-LDH and ZIF-67, Co-LDH@ZIF-67 exhibited prominent activity and stability in OER
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