Carbon Aerogels Loaded\nwith Noble Metal Nanocrystal\nElectrocatalysts for Efficient Full Water Splitting

Abstract

It is always a challenge to improve the stability of\nthe electrocatalyst\nand reduce noble metal loading in the process of hydrogen production\nfrom electrolytic water. Herein, we have designed a general carbon\naerogel (CG) loaded with noble metal ultrafine nanocrystalline electrocatalysts\nfor efficient full water splitting. The precursor polyethyleneimine/polydopamine\nco-modified cellulose nanocrystal (CNC)-loaded noble metal by the\nhydrothermal method and carbonized at high temperature to produce\nthe CG-loaded noble metal ultrafine nanocatalysts (size < 2.5 nm).\nThrough the control of components, different nanocatalysts (defined\nas CG-M-X, M as Pt and Ir and X as the quantity score) exhibit extraordinary\nelectrocatalytic activity. To achieve a catalytic current of 10 mA\ncm^–2 in 1 M KOH electrolyte, the overpotential required\nfor hydrogen evolution was 23.6 mV for CG-Pt-1.19% and 242 mV for\noxygen evolution in CG-Ir-1.62%. When assembled into the full water\nsplitting system, CG-Pt-1.19%||CG-Ir-1.62% delivers a current density\nof 10 mA cm^–2 at a low voltage of 1.43 V, which\ncan steadily drive the complete decomposition of water at nearly 100%\nFaraday efficiency for up to 50 h without any significant performance\ndegradation. Furthermore, the Pt₃₈ cluster model is constructed,\nthe electrolytic water activity on the Pt₃₈ cluster is\nhigher than the Pt(111) surface, and the N doping on CG regulates\nthe local electric field of Pt₃₈ cluster, which is more\nconducive to the electrocatalytic hydrogen evolution reaction.