Metal-Organic Powder Thermochemical Solid-Vapor Architectonics toward Gradient Hybrid Monolith with Combined Structure-Function Features

Abstract

The conversion of inorganic powders or metal powders into gradient components is typically achieved with the help of a non-uniform electric or pressure field. However, the current technologies are ineffective in converting powder into gradient-structured hybrid components with combined structure-function features because of the lack of a non-uniform field to control evolution of the structures. The present work addresses this challenge by taking advantage of uniformly distributed metal nanoparticles and non-uniformly distributed reactive gases generated during thermopyrolysis of metal-organic powder to generate gradient metal-carbon monolith via combined chemical vapor deposition and solid-state welding. The obtained monolith shows good mechanical strength and high catalytic activity, allowing it to be used as a working electrode for a seawater battery. This method connecting gas-solid-state synthesis together with processing may lead to other gradient hybrid monoliths in the future.A gradient carbon-metal hybrid component can be manufactured by thermopyrolysis of metal-organic framework powder. The non-uniformly distributed carbonaceous vapor and uniformly dispersed Co nanoparticles are essential for generating the gradient carbon monolith. This monolith exhibits good mechanical strength and high catalytic activity, and thus can be directly utilized as an electrode for a Mg/HO battery to generate electricity from seawater. The assembled battery shows power density comparable with that of a battery with Pt as the electrode.Direct manufacturing from powder to final component is of great significance for industry. However, it remains a challenge to develop a one-pot “powder-to-product” strategy to produce gradient hybrid components with combined structural and functional advantages. In this work, we report metal-organic powder thermochemical solid-vapor architectonics to direct zeolitic imidazolate framework powder into gradient cobalt/carbon monolith by utilizing in situ generated reactive vapor (non-uniform distribution) and Co nanoparticles (uniformly distributed) to achieve a combination of chemical vapor deposition/growth and solid-state welding. The gradient hybrid monolith possesses good mechanical stability, allowing it to be directly used as a freestanding working electrode for hydrogen evolution reaction in a seawater battery. This catalyst shows a low overpotential of 84 mV at a current density of 10 mA cm. Furthermore, a stable power generation of over 168 h in seawater has also been realized.