A High Faraday Efficiency NiMoO<sub>4</sub> Nanosheet Array Catalyst by Adjusting the Hydrophilicity for Overall Water Splitting
Zining Wang, Hui Wang, Shan Ji, Xuyun Wang, Pengxin Zhou, Shuhui Huo, Vladimir Linkov, Rongfang Wang
Abstract
Abstract To obtain a highly active, stable, and binder‐free electrode based on transition‐metal compounds for water splitting, nickel foam‐supported 3D NiMoO 4 nanosheet arrays modified with 0D Fe‐doped carbon quantum dots (Fe‐CQDs/NiMoO 4 /NF) are synthesized. The structure characterizations indicated that 0D Fe‐CQDs are evenly dispersed onto the NiMoO 4 sheets of the arrays. The contact angle analysis confirmed that the surface hydrophilia of the arrays is improved after the 0D Fe‐CQDs are deposited 3D on the NiMoO 4 sheets. Here, both the activity and durability in electrochemical water splitting are significantly enhanced with the Fe‐CQDs/NiMoO 4 /NF catalysts. At a current density of 10 mA cm −2 , the resultant Fe‐CQDs/NiMoO 4 /NF revealed an overpotential of only 117 mV for the hydrogen evolution reaction (HER), a relatively low overpotential of 336 mV toward the oxygen evolution reaction (OER), and a Faraday efficiency of up to 99 %. This performance can be attributed to the unique 3D nanosheet array structure, the synergistic effect, and the optimal hydrophilia for gas evolution evolved from the electrode surface.