不同晶面的銀奈米晶體於析氫反應之光催化活性

Abstract

本研究利用波長450 nm、532 nm以及808 nm之雷射，照射不同晶面的銀奈米晶體，探討其應用於析氫反應之光電催化活性。由於侷域化表面電漿共振現象，銀奈米十四面體在波長450 nm之雷射的照射下，其析氫效率有所提升，電流密度值從原本的-20.23 mA/cm2增加至-20.50 mA/cm2，產生了0.27 mA/cm2的光電流密度。而在犧牲試劑的作用之下，光電流密度則可達到0.403 mA/cm2。 在不同形狀之銀奈米晶體的光電催化效率探討中，以銀奈米八面體的表現最佳。相較於銀奈米立方體與銀奈米十四面體的光電流密度值(分別為7.5×〖10〗^(-6)和1.5×〖10〗^(-5) mA/cm2·mW)，銀奈米八面體具有最高的光電流密度(6.8×〖10〗^(-5) mA/cm2·mW)。這是由於比起[100]晶面，氫原子較易吸附在銀奈米晶體的[111]晶面。所以，於[111]晶面上，氫分子較容易被生成出來，進而造成電流密度的提升。因此，[111]晶面的銀奈米八面體，應用於析氫反應，具有出色的光電催化效率。The facet-dependent photoelectrocatalytic activities of silver nanocrystals on carbon fiber paper (CFP) were investigated for hydrogen evolution reaction (HER) under the laser irradiation at wavelengths of 450, 532 and 808 nm, respectively. Under the laser irradiation at wavelength of 450 nm, the hydrogen generation of silver cuboctahedra was improved due to localized surface plasmon resonance (LSPR), that the current density was shift from -20.23 to -20.50 mA/cm2 and the photocurrent density was reached to 0.27 mA/cm2. Furthermore, photocurrent density of silver cuboctahedra was increased from 0.270 to 0.403 mA/cm2 by the assist of hole scavenger. Among different shapes of silver nanocrystals, silver octahedra exhibited the best performance for the photoelectrocatalysis. Compared with the photocurrent density of silver nanocubes and silver cuboctahedra (7.5×〖10〗^(-6) and 1.5×〖10〗^(-5) mA/cm2·mW respectively), the photocurrent density of silver octahedral (6.8×〖10〗^(-5) mA/cm2·mW) was highest. The reason can be ascribed that the adsorption of hydrogen atom on the planar [111] surface of silver nanocrystals is easier than [100]. Therefore, hydrogen can be produced more effectively on the [111] surface to result in the increase of current density. Overall, the silver octahedra with the [111] surface showed the high efficiency for photoelectrocatalysis in HER application.