In Situ Reconstructed Layered Double Hydroxides via MOF Engineering and Ru Doping for Decoupled Acidic Water Oxidation Enhancement

Abstract

Discovering cost-effective, durable, and economical electrocatalysts for the lattice oxygen-mediated mechanism (LOM)based oxygen evolution reaction (OER) under acidic conditions is essential for advancing the commercialization of electrochemical water-splitting devices. In this study, we effectively constructed a distinctive petal-like nanoflake (NFls) structure by introducing ruthenium (Ru) into a NiM (M = Fe, Co) metal−organic framework (MOF) on a nickel foam (NFo) substrate through a straightforward in situ conversion process of layered double hydroxides (LDHs). Utilizing the unique electrochemical properties of this material, the Ru-doped NiFe-BDC/NFo exhibited an impressively low overpotential of ∼247 mV at a current density of 10 mA cm −2 when operating in an acidic environment for OER. Most notably, our champion catalysts displayed exceptional long-term stability during continuous operation for 20 h in 0.5 M H 2 SO 4 , positioning them as some of the top electrocatalysts for acidic conditions. The exceptional catalytic performance of NiM (M = Fe, Co)-BDC/NFo can be ascribed to the introduction of Ru and the conversion of LDH into a MOF. This transformation significantly enhances reaction kinetics and facilitates charge transfer, ultimately resulting in the attainment of optimal activity for the OER. This research introduces a novel category of electrocatalysts for the OER under acidic conditions, which has been relatively underexplored.

A Review on Highly Efficient Ru-Based Electrocatalysts for Acidic Oxygen Evolution Reaction

“…Three-dimensional (3D) nanomaterials have garnered significant interest due to their high specific surface area, controllable 3D configuration, and multidimensional rich pore structure. − For example, 3D sea urchin-like spheres composed of nanorods (Figure n) not only facilitated mass transfer but also exposed a great number of active sites, thereby exhibiting superior OER activity . In addition, metal–organic frameworks (MOFs) with high porosity, adjustable pore diameter, and high active site density can be used as structure-directing agents to fabricate 3D porous materials. − For example, Zhuang et al designed an open 3D hollow RuIrO x nanonetcages structure with abundant mesopores (Figure o), which exposed more active sites and achieved high atomic utilization, thereby boosting the OER process . MOFs also can serve as templates for the synthesis of hollow high-entropy metal oxides (HEO).…”

A bimetallic NiFe MOF with ultra-thin two-dimensional nanosheet structure effectively accelerates oxygen evolution reaction

“…Currently, commercial electrocatalysts for OER are precious metal-based catalysts, such as RuO 2 and IrO 2 . 6,7 However, the scarcity, high cost, and instability of precious metal-based catalysts limit their widespread use. 8,9 As a result, developing cheap and efficient catalysts to reduce the OER reaction energy barrier and improve the efficiency of electrolytic water splitting 10,11 has become a challenge.…”