Tạo ra khiếm khuyết, chuyển giao d-d và giảm khoảng cách năng lượng trong nanoparticle TiO2 doped Cu

International Nano Letters - Tập 3 - Trang 1-8 - 2013
Biswajit Choudhury1, Munmun Dey1, Amarjyoti Choudhury1
1Department of Physics, Tezpur University, Napaam, India

Tóm tắt

TiO2 bị dop Cu2+ kích thích sự hình thành pha brookite cùng với anatase. Việc bổ sung Cu2+ tạo ra các khiếm khuyết cấu trúc trong TiO2. Bằng chứng trực tiếp là những đỉnh khuếch tán yếu và rộng. Các đỉnh Raman của TiO2 dop cũng rộng và bị dịch sang tần số cao hơn. TiO2 nguyên chất thể hiện sự hấp thụ trong vùng UV, vị trí của nó bị dịch về phía vùng khả kiến khi bổ sung Cu vào. Các đỉnh hấp thụ khả kiến xuất hiện do sự chuyển giao d-d của Cu2+ trong môi trường tinh thể của TiO2. Việc bổ sung Cu2+ làm biến dạng cấu trúc cục bộ của TiO2, dẫn đến mất đối xứng bát diện xung quanh Cu2+. Biến dạng Jahn-Teller tách biệt trạng thái 2Eg và 2T2g của Cu2+ thành nhiều trạng thái d. Sự tương tác của ánh sáng kích thích electron từ trạng thái cơ bản lên nhiều trạng thái kích thích, tạo ra các đỉnh hấp thụ khả kiến trong khung của TiO2. Những trạng thái d của Cu2+ và khiếm khuyết oxy tạo ra các trạng thái dải, qua đó thúc đẩy quá trình chuyển giao điện tử đến những mức này và dẫn đến việc giảm khoảng cách năng lượng của TiO2. Một xác nhận trực tiếp là sự tăng cường cường độ năng lượng Urbach với sự giảm đi về khoảng cách năng lượng của TiO2 dop.

Từ khóa


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