Competitive Coordination-Oriented Monodispersed Ruthenium Sites in Conductive MOF/LDH Hetero-Nanotree Catalysts for Efficient Overall Water Splitting in Alkaline Media

Rational exploration of efficient, inexpensive, and robust electrocatalysts is critical for the efficient water splitting. Conjugated conductive metal-organic frameworks (cMOFs) with multicomponent layered double hydroxides (LDHs) to construct bifunctional heterostructure catalysts are considered as an efficient but complicated strategy. Here, the fabrication of a cMOF/LDH hetero-nanotree array catalyst (CoNiRu-NT) coupled with monodispersed ruthenium (Ru) sites via a controllable grafted-growth strategy is reported. Rich-amino hexaiminotriphenylene linkers coordinate with the LDH nanotrunk to form cMOF nanobranches, providing numerous anchoring sites to precisely confine and stabilize Ru-N-4 sites. Moreover, monodispersed and reduced Ru moieties facilitate H2O adsorption and dissociation, and the heterointerface between the cMOF and the LDH further modifies the chemical and electronic structures. Optimized CoNiRu-NT displays a significant increase in electrochemical water-splitting properties in alkaline media, affording low overpotentials of 22 mV at 10 mA cm(-2) and 255 mV at 20 mA cm(-2) for the hydrogen evolution reaction and oxygen evolution reaction, respectively. In an actual electrochemical system, CoNiRu-NT drives an overall water splitting at a low cell voltage of 1.47 V to reach 10 mA cm(-2). This performance is comparable to that of pure noble-metal-based materials and superior to most reported MOF-based catalysts.

Automated summary

This study reports a highly efficient electrocatalyst for water splitting, which is fabricated using a controllable grafted-growth strategy to form a cMOF/LDH hetero-nanotree array catalyst coupled with monodispersed ruthenium (Ru) sites. The optimized catalyst shows excellent electrochemical water-splitting properties in alkaline media, outperforming most reported MOF-based catalysts.