鹵化鉛鈣鈦礦奈米晶體光催化氮氣還原反應

Abstract

鹵化鉛鈣鈦礦除了在光電領域取得了驚人的成就外，由於其合適的能帶結構、較長的載流子擴散長度及優異的電荷轉移能力，在光催化領域也引起了廣泛討論。然而，水氣不穩定性限制了它們在氮還原反應(NRR)中的應用。本研究通過將錳離子摻雜到 CsPbBr3 奈米片(NPLs)中合成具有自旋極化電子的光催化劑，以提高乙酸乙酯系統中的氮還原效率。從電子顯微鏡觀察得知，錳離子摻雜不會改變CsPbBr3 NPLs的形貌與尺寸。根據X光粉末繞射光譜、吸收光譜和光致發光 (PL) 光譜的量測，確認錳離子成功摻入CsPbBr3 NPLs 結構。由於自旋極化電子的產生，錳摻雜的CsPbBr3 NPLs表現出優異的氮氣還原活性，NH3的產率從31.47 μmol g-1增加到89.31 μmol g-1。更重要的是，錳摻雜的 CsPbBr3 NPL 在外部磁場(0.3 T)下的光催化氮還原反應性能提高了兩倍。藉由在有和沒有外部磁場(0 和 0.3 T)的條件下，使用 PL 光譜和時間分辨 PL 光譜對反應機制進行探討，證實外部磁場(0.3 T)對光催化性能的提高歸因於更長的載流子壽命，以及在反應過程中更有效的抑制載流子復合。Lead halide perovskites have not only made amazing achievements in the field of optoelectronics, but also aroused extensive discussion in the field of photocatalysis due to their suitable band gap, long charge carrier diffusion length and excellent charge transfer ability. However, moisture instability limits their application in photocatalytic nitrogen reduction reaction (NRR). In this study, photocatalyst with spin-polarized electrons is synthesized by doping manganese ions into CsPbBr3 nanoplates (NPLs) to improve the nitrogen reduction efficiency in ethyl acetate system. From the observation of electron microscope, it is known that the doping with manganese ions does not change the shape and size of the CsPbBr3 NPLs. According to powder X-ray diffraction spectroscopy, absorption, and photoluminescence (PL) spectra, the incorporation of manganese ions into CsPbBr3 NPLs structure is successful. Due to the generation of spin-polarized electrons, the Mn-doped CsPbBr3 NPLs exhibit excellent nitrogen reduction activity, and the yield of NH3 is increased from 31.47 μmol g–1 to 89.31 μmol g–1. The improvement of NRR efficiency is mainly attributed to the increasing spin-polarized electrons by doping manganese ion. More importantly, Mn-doped CsPbBr3 NPLs exbibit two times improved performance of photocatalytic nitrogen reduction reaction with an external magnetic field (0.3 T). The mechanism is well-investigated by PL spectra and time-resolved PL spectroscopy with and without an external magnetic field (0 and 0.3 T). The enhancement of photocatalytic performance with an external magnetic field (0.3 T) is attributed to a longer carrier lifetime and the suppression of carrier recombination are achieved during the reaction.