Surfactant-Free Approach for Engineering an Ultrathin Ti-Doped Ni(OH) Nanosheet on Carbon Cloth: Experimental and Theoretical Insight into Boosted Alkaline Water Oxidation Activity.

Ti-based layered double hydroxides (LDHs) have enormous potential in photocatalysis, electrocatalysis, and photoelectrocatalysis. However, Ti-based LDHs are rarely reported because of the difficulties of the preparation process, in which the Ti precursors are more prone to hydrolysis into titanium hydroxide. In this work, toward robust, efficient, and earth-abundant electrocatalysts for water oxidation in alkaline environments, we have engineered Ti-doped Ni(OH) nanosheet arrays on carbon cloth [Ti-Ni(OH)/CC] with a facile solvothermal and surfactant-free method. The experimental tests show that the activity of Ti-Ni(OH)-1/CC (∼12.5 atom % Ti substitution) is optimal among these materials. In addition, the activity is correlated with the Ti substitution ratio and reversed with higher Ti doping level (≥25 atom % Ti substitution). Therein, η of Ti-Ni(OH)-1/CC is as low as 196 mV, and it is still maintained at 210 mV after a long-term chronopotentiometry (CP) test at a constant current density of 10 mA cm for 32 h, demonstrating superior activity and long-term durability. Density functional theory calculations further reveal that dilute Ti substitution produces extra active sites and promotes more optimal OH* adsorption to the surface of the electrocatalyst.