Carbon Aerogels Loaded with Noble Metal Nanocrystal Electrocatalysts for Efficient Full Water Splitting
Wenhui Wang, Zhenping Pan, Zhen Zhang, Yihua Zhu, Jianhua Shen
Abstract
It is always a challenge to improve the stability of the electrocatalyst and reduce noble metal loading in the process of hydrogen production from electrolytic water. Herein, we have designed a general carbon aerogel (CG) loaded with noble metal ultrafine nanocrystalline electrocatalysts for efficient full water splitting. The precursor polyethyleneimine/polydopamine co-modified cellulose nanocrystal (CNC)-loaded noble metal by the hydrothermal method and carbonized at high temperature to produce the CG-loaded noble metal ultrafine nanocatalysts (size < 2.5 nm). Through the control of components, different nanocatalysts (defined as CG-M-X, M as Pt and Ir and X as the quantity score) exhibit extraordinary electrocatalytic activity. To achieve a catalytic current of 10 mA cm –2 in 1 M KOH electrolyte, the overpotential required for hydrogen evolution was 23.6 mV for CG-Pt-1.19% and 242 mV for oxygen evolution in CG-Ir-1.62%. When assembled into the full water splitting system, CG-Pt-1.19%||CG-Ir-1.62% delivers a current density of 10 mA cm –2 at a low voltage of 1.43 V, which can steadily drive the complete decomposition of water at nearly 100% Faraday efficiency for up to 50 h without any significant performance degradation. Furthermore, the Pt 38 cluster model is constructed, the electrolytic water activity on the Pt 38 cluster is higher than the Pt(111) surface, and the N doping on CG regulates the local electric field of Pt 38 cluster, which is more conducive to the electrocatalytic hydrogen evolution reaction.