The development of efficient electrocatalysts through heterostructure engineering is crucial for boosting the oxygen evolution reaction (OER) kinetics. Herein, we demonstrate a hierarchical MIL-53/NiCu-LDH(12) heterostructure in-situ grown on nickel foam (NF), where the MIL-53 component is controllably constructed on NiCu-LDH/NF to establish robust interfacial contact and electronic coupling. This multi-level architecture synergistically endows the catalyst with enlarged electrochemical active surface area, abundant accessible active sites, accelerated electron transfer kinetics, and reduced band gap. Remarkably, operando characterization reveals that the heterojunction undergoes partial structural reconstruction during OER to generate γ-FeOOH/γ-NiOOH active phases. The formed Fe-O-Ni bridging bonds facilitate interfacial charge redistribution, which effectively modulates the electronic configuration and optimizes reaction intermediates adsorption. Benefiting from these merits, the MIL-53/NiCu-LDH(12)/NF electrode delivers exceptional alkaline OER performance, requiring ultralow overpotentials of 160 and 226 mV to achieve current densities of 10 and 100 mA cm −2 , respectively, along with a small Tafel slope of 42 mV dec −1 . This work proposes an innovative strategy integrating hierarchical architecture design with interfacial electronic modulation for developing advanced transition metal-based OER electrocatalysts.
Yi Zheng,Yibai Sun,Qi Wang,Ronghui Xu,Yingping Zheng,Jinxi Chen,Yongbing Lou
The design of an efficient oxygen evolution reaction (OER) catalyst is significant for water splitting. Telluride-based materials exhibit exceptional electrical conductivity and mass transfer properties, yet their application in electrocatalysis remains constrained by limited active site exposure. Conversely, layered double hydroxides possess unique granular/lamellar morphologies that offer significant potential for active site amplification through strategic morphology regulation. In response to the demand for highly efficient and stable OER electrocatalysts, this study presented a rationally designed heterostructure. NiTe nanorods were first grown on nickel foam (NF), followed by intimate coupling with granular nickel-copper layered double hydroxide (NiCu-LDH). Ultimately, a well-defined core-shell structure of NiCu-LDH/NiTe@NF was successfully constructed. Unlike conventional 2D nanosheets, the NiCu-LDH exhibited unique low-crystallinity characteristics, resulting in a crystalline-amorphous heterostructure that provided abundant unsaturated coordination sites, thereby effectively facilitating the adsorption and conversion of reaction intermediates. Benefiting from the optimized interfacial electronic structure and rapid charge transfer capability, the composite catalyst exhibited an overpotential of only 315 mV at a current density of 100 mA cm −2 and maintained stable operation for over 160 h at 50 mA cm −2 with negligible performance degradation. Mechanistic studies revealed that the formation of NiOOH acts as the true active species, significantly enhancing OER performance. This work not only offered a high-performance OER electrocatalyst, but also provided new insights into the rational design of crystalline-amorphous composite materials.
Sulfurization-induced in situ surface reconstruction generates a Ni³⁺-rich NiOOH active phase for enhanced AOR activity. • Ni–Cu interaction optimizes interfacial electron transfer and promotes ammonia oxidation kinetics. • Cu/NF cathode promotes NO₃⁻/NO₂⁻ intermediate reduction and improves N₂ selectivity. • Anode–cathode synergistic catalysis integrates active phase reconstruction with intermediate regulation. • The integrated electrocatalytic system achieves > 98% NH₄⁺-N removal with high N₂ selectivity under mild conditions. Electrocatalytic ammonia oxidation (AOR) is a promising strategy for efficient ammonia removal and recovery; however, its practical application remains limited by sluggish reaction kinetics and low N₂ selectivity, while the structure–activity relationship between catalyst surface reconstruction and catalytic performance remains poorly understood. Herein, a sulfurization-modified NiCu layered double hydroxide (S-NiCu-LDH/NF) anode coupled with a Cu/NF cathode was rationally constructed to establish an anode–cathode synergistic electrocatalytic system for efficient NH₄⁺-N oxidation and selective nitrogen conversion. The optimized system achieved over 98% NH₄⁺-N removal within 90 min with an N₂ selectivity exceeding 82%. Electrochemical analyses reveal that sulfurization improves interfacial charge-transfer kinetics, while the Cu/NF cathode further facilitates electron transport through reduced charge-transfer resistance. XPS and Raman analyses suggest that sulfurization induces in situ surface reconstruction during electrolysis, accompanied by the formation of a Ni³ ⁺-rich NiOOH active phase. The reconstructed active phase is proposed to facilitate NH₃ activation and the adsorption and conversion of key reaction intermediates, thereby promoting multi-electron transfer during AOR. Meanwhile, the Cu/NF cathode promotes the electrochemical conversion of NO₂⁻ and NO₃⁻ intermediates, suppressing their accumulation and consequently improving N₂ selectivity through an anode–cathode synergistic process. Download: Download high-res image (232KB) Download: Download full-size image
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