Laser‐Induced Annealing of Metal–Organic Frameworks on Conductive Substrates for Electrochemical Water Splitting

Abstract

The conventional thermal transformation of metal–organic frameworks (MOFs) for electrocatalysis requires high temperature, an inert atmosphere, and long duration that result in severe aggregation of metal particles and non‐uniform porous structures. Herein, a precise and inexpensive laser‐induced annealing (LIA) strategy, which eliminates particle aggregation and rapidly generates uniform structures with a high exposure of active sites, is introduced to carbonize MOFs on conductive substrates under ambient conditions within a few minutes. By systematically considering 8 substrates and 12 MOFs, a series of LIA‐MOF/substrate devices with controllable sizes and good flexibility are successfully obtained. These LIA‐MOF/substrate devices can directly serve as working electrodes. Remarkably, LIA‐MIL‐101(Fe) on nickel foam exhibits an ultralow overpotential of 225 mV at a current density of 50 mA cm−2 and excellent stability over 50 h for facilitating the oxygen evolution reaction, outperforming most recently reported transition‐metal‐based electrocatalysts and commercial RuO2. Physical characterizations and theoretical calculations evidence that the high activity of LIA‐MIL‐101(Fe) arises from the favorable adsorption of intermediates at its Ni‐doped Fe3O4 overlayer that is formed during the laser treatment. Moreover, the LIA‐MOF/substrate devices are assembled for overall water splitting. The proposed LIA strategy demonstrates a cost‐effective route for manufacturing scalable energy storage and conversion devices.

Oxygen‐Rich Cobalt–Nitrogen–Carbon Porous Nanosheets for Bifunctional Oxygen Electrocatalysis

“…abundant N-containing ligands and active metal elements. [27][28][29][30][31][32][33][34] The morphology, structure, porosity, and active metal content of ZIF-based precursors can be easily controlled by many synthetic strategies to achieve accelerated charge and mass transport, accessible active M-N x sites, as well as optimized M-N x coordination configurations in the ZIF-derived M-N-C catalysts. [9,27] Despite the certain catalytic performance of M-N-C catalysts having been improved to some extent, the overpotentials for OER are higher than 0.3 V at the current density of 10 mA cm −2 owing to the lack of intrinsic M-O x active sites.…”

Ni/Co/Co3O4@C nanorods derived from a MOF@MOF hybrid for efficient overall water splitting

“…[29][30][31] Moreover, laser-scribing capable of ultrafast heating and cooling has been recently recognized as a fast and effective way to transform MOFs into nanoporous metallic carbon composites. 32,33 It has been demonstrated that the size, uniformity, and even phase of the produced materials can be precisely controlled by laser-scribing. 34 Therefore, microwavebased synthesis combined with laser-scribing could be a facile method to massively synthesize nanostructured MOF-derived catalysts with multimetallic active species (Fig.…”

Chromium-Modified Ultrathin CoFe LDH as High-Efficiency Electrode for Hydrogen Evolution Reaction

“…The most efficient electrode for HER is still noble metal Pt or Pt/C. Nevertheless, the high expense and insufficient reserves of Pt limit its utility in industrial scale [ 3 ].…”