Carbon black structural effect within kraft black liquor-based poly(HIPE): enhanced hydrogen storage and electro-capacitive properties

Abstract

A biopolymer derived from Kraft Black Liquor (KBL), a byproduct of the paper industry composed mainly of lignin and hemicellulose, has been successfully filled with three different types of carbon black (CB) that differ in their specific surface areas, sizes, shapes and surface heteroatoms. These composite CB–KBL dispersions have been subsequently employed to generate porous monoliths through an emulsion-polymerization templating process. After carbonization, the fillers' influence over the resulting carbon monolith structures and textures is investigated. In particular, beyond XRD, Raman spectroscopy demonstrates improved sample structuration through CB filler addition while nitrogen sorption measurements reveal the influence of the fillers over the final composite's porosities. Considering their properties and effectiveness, hydrogen storage at 77 K reveals that some materials offer up to 1.4 wt% of H₂ storage capacity, being higher than that of some commercial carbon materials (with the same specific surface) offering 1.2 wt% hydrogen retention. When addressing their electrochemical energy storage properties, some of these electrode materials deliver extremely promising specific capacities and rate capabilities, with values up to 47 mA h g⁻¹ at 1 A g⁻¹ in alkaline electrolyte, higher than those of the well-known “YP-80F” commercial material tested under the same conditions. These enhanced energy storage properties, while employing a high tonnage paper industry by-product as a carbonaceous source and carbon blacks as structural and textural modifiers, render these materials realistic candidates favoring a sustainable energy transition.