銀奈米粒子輔助之矽微米結構應用於水分解之光陰極

Abstract

本研究中，我們將p型矽晶片蝕刻成矽微米柱陣列，由於矽微米柱結構減少了電子傳輸至與水介面之距離與提供電子單一傳輸方向，故增強光電流訊號。此外，我們將電漿粒子修飾於矽微米柱上藉表面電漿共振效應增加水分解效率。表面電漿共振具兩種現象，其一，電漿粒子上鄰近費米能階之電子被激發至較高能階形成熱電子，且足以克服蕭基能障進入矽微米柱之導電帶，致使增加光電流。第二，產生電場促使矽微米柱上之表面產生電子-電洞對，並減少電子-電洞再復合現象。於表面電漿共振之效應下，有效提升光電流，於參考電極為銀/氯化銀電極，外加偏壓-1 V下，可測得光電流約42 mA/cm2 。In this study, we etched p-type silicon wafer to fabricate silicon microwires. The photocurrent of silicon wires is enhanced owning to the shorter diffusion length for minor carrier and the single conduction direction for major carrier. In addition, we utilized plasmonic nanoparticles to modify silicon wires to further promote its water splitting efficiency by surface plasmon resonance. The electrons near the Fermi level of the plasmonic nanoparticles are excited to higher level state forming hot electrons by surface plasmon resonance (SPR). The hot electrons overcome the Schottky barrier injecting into the conduction band of Si wires and increase its photocurrent. Besides, the electromagnetic fields generated from SPR increase the possibility of the electron-hole pairs forming near the surface of Si wires and decrease their recombination. Under the assistance from the SPR, the water splitting efficiency of could be strongly enhanced. The significant enhancement of the photocurrent to 42 mA/cm2 is observed on the silver nanoparticles modified silicon wires.