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

Abstract

production of pure H 2 ; this technique can be coupled with other instantaneous energy conversion techniques. [2] However, the sluggish reaction kinetics of both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) limit the application of water splitting. [3] So far, ruthenium-(Ru-), iridium-(Ir-), and platinum-(Pt-) based materials, such as noble metal oxides, [4] noble-metal single-atom catalysts, [5] and hetero-structured noblemetal-based catalysts [6] are still the most efficient HER and OER catalysts. However, their high costs and low stability greatly limit their practical application. Great efforts has been devoted to exploring novel inexpensive bifunctional catalysts for efficient overall water splitting. [7] In particular, the development of non-noble-metal-based catalysts under alkaline conditions, which require several-fold high catalytic activity due to the ultralow proton activity in alkaline solution, was found to be an attractive but challenging approach. [8] Dispersing ultralow-content noble metals on nonprecious material platforms is an effective improvement strategy. This approach not only improves the adsorption capabilities of hydrogen-and oxygencontaining intermediates and accelerates the reaction kinetics of both the HER and OER, [9] but also balances the performance and cost. Multimetal-based layered double hydroxides (LDHs) can be utilized as support materials owing to their low cost, 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, mono dispersed and reduced Ru moieties facilitate H 2 O 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.

Construction of MnxCoyO4/Ti electrocatalysts for efficient bifunctional water splitting

“…The required voltages of Co x P–Fe 3 P, CoP/CNFS and NiFeOP are 1.62, 1.65 and 1.69 V, respectively. 65–67 Compared with the performance of catalysts reported in the literature (Table S3†), the results indicate that Mn x Co y O 4 /Ti can be comparable to many high-performance catalysts. Mn x Co y O 4 /Ti (Mn : Co = 1 : 2) exhibits excellent bifunctionality and can be used as a promising catalyst for two half reactions in water splitting.…”

Assembled cobalt phosphide nanoparticles on carbon nanofibers as a bifunctional catalyst for hydrogen evolution reaction and oxygen evolution reaction

“…In particular, the intrinsic catalytic activity of the catalyst can also be optimized by manipulating its surface electronic structure through interface engineering to form heterostructures. 36–38 Metal–organic frameworks (MOFs), a new category of porous materials, have been widely used in areas like gas storage, 39 catalysis, 40–43 biomedicine, 44 and electrochemistry. 45–47 Recently, there has been an increasing tendency to use MOFs as a precursor to synthesize CNTs.…”

Double functionalization of Mo 2 C and NiMn‐LDH assembling g‐C 3 N 4 as efficient bifunctional electrocatalysts for selective electrocatalytic reactions and overall water splitting

“…6,7 Therefore, efforts were currently underway to develop various electrocatalysts with different characteristics and excellent HER and OER performance for overall water splitting applications. [8][9][10][11] As we all know, noble metal oxides (such as IrO 2 /RuO 2 et al) and noble metals (such as Pt) have extremely low overpotentials during HER and OER processes, respectively, which can greatly reduce the barrier required for water splitting. [12][13][14] Generally speaking, to obtain an electrocatalyst with both OER and HER functions, mixing the two materials (such as IrO 2 + Pt) is a common method, and it is easy to identify the active components of the different reactions.…”

“…Among them, the anode OER reaction is slow due to the high potential barrier, which greatly limits the hydrogen production efficiency of the cathode 6,7 . Therefore, efforts were currently underway to develop various electrocatalysts with different characteristics and excellent HER and OER performance for overall water splitting applications 8‐11 . As we all know, noble metal oxides (such as IrO 2 /RuO 2 et al) and noble metals (such as Pt) have extremely low overpotentials during HER and OER processes, respectively, which can greatly reduce the barrier required for water splitting 12‐14 .…”