Ultrathin and dense Ag nanosheets synthesis under suppressed face (111) growth and surface diffusion

Ultrathin and dense Ag nanosheets (ANS) with large electrochemically active surface area and rich edge active sites over Ag foils are synthesized via a facile electrodeposition approach in a double electrode system. By adjusting the concentration of H₃BO₃ and changing deposition temperature, ANS with varying thickness are fabricated. Interestingly, ANS gradually become thinner with H₃BO₃ concentration increasing, as BO₃^3- ions preferentially adsorb on the Ag (111) faces, thereby inhibit the growth of Ag on the (111) faces. Furthermore, the morphologies and dimensions of ANS are also found to strongly depend on the deposition temperature. Thinner and denser ANS are more easily obtained at low deposition temperature as it can suppress the surface diffusion of Ag atoms, while when the deposition temperature is high, thinner and denser ANS can only be obtained at high H₃BO₃ concentration. Especially, ANS fabricated with 0.5 M H₃BO₃ at 0 °C (ANS-0.5M-0°C) with an ultrathin thickness of about 11 nm exhibits a remarkable CO Faradaic efficiency of 97.11% and the total current density of −11.50 mA cm⁻² at −0.9 V vs. the reversible hydrogen electrode towards CO₂ electroreduction.