A High Faraday Efficiency NiMoO4 Nanosheet Array Catalyst by Adjusting the Hydrophilicity for Overall Water Splitting

To obtain a highly active, stable, and binder‐free electrode based on transition‐metal compounds for water splitting, nickel foam‐supported 3D NiMoO4 nanosheet arrays modified with 0D Fe‐doped carbon quantum dots (Fe‐CQDs/NiMoO4/NF) are synthesized. The structure characterizations indicated that 0D Fe‐CQDs are evenly dispersed onto the NiMoO4 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 NiMoO4 sheets. Here, both the activity and durability in electrochemical water splitting are significantly enhanced with the Fe‐CQDs/NiMoO4/NF catalysts. At a current density of 10 mA cm−2, the resultant Fe‐CQDs/NiMoO4/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. Water loving, water splitting: 0D carbon quantum dot (CQD)‐modified 3D NiMoO4 nanosheets with hierarchical structure were designed and synthesized by a two‐step and facile procedure. As a result, the obtained NM‐FC samples were revealed to exhibit a superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance in terms of activity, stability, and fast kinetics in KOH electrolyte.