CƠ CHẾ HÌNH THÀNH VÀ TỔNG HỢP CÁC SIÊU CẤU TRÚC ZnO TINH THỂ CAO BẰNG PHƯƠNG PHÁP SOL-GEL: QUÁ TRÌNH BIẾN ĐỔI TỪ CẤU TRÚC VI CẦU RỖNG ĐẾN HÌNH THÁI HỌC DẠNG HOA

0 Người đánh giá. Xếp hạng trung bình 0

Tác giả: Thế Sơn Lê

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Journal of Science and Technique: Section on Physics and Chemical Engineering, 2024

Mô tả vật lý: tr.101

Bộ sưu tập: Báo, Tạp chí

ID: 439271

Thêm vào giỏ Liên kết toàn văn

Các siêu cầu ZnO rỗng và xốp (HP) với cấu trúc nguyên vẹn có ứng dụng trong nhiều lĩnh vực khác nhau. Tuy nhiên, việc tổng hợp vật liệu như vậy gặp rất nhiều khó khăn. Nghiên cứu này góp phần vào việc tối ưu hóa quy trình điều chế siêu cầu HP ZnO với độ kết tinh cao bằng phương pháp sol-gel, đề xuất cơ chế hình thành và khả năng sử dụng các siêu cầu HP ZnO để tạo ra ZnO dạng cấu trúc hình hoa với cấu trúc 3D phức tạp hơn. Trong điều kiện phản ứng nhiệt dung môi ở 200°C, bằng cách sử dụng zinc acetate (0,065 M) trong diethylene glycol với các tỉ lệ mol H2O/Zn khác nhau, đã tổng hợp được một loạt vật liệu ZnO ở dạng hạt kích thước nanomet và dạng siêu cầu. Trong phạm vi tỉ lệ mol 2 - 4, các hạt nano ban đầu tự tập hợp thành các siêu cầu rắn và xốp (SP), phát triển chủ yếu về phía hoặc dọc theo trục c, tạo ra các siêu cầu HP với cấu trúc rỗng nguyên vẹn. Ngược lại, tỉ lệ mol 6 - 20 chỉ tạo ra tinh thể nano riêng biệt thay vì siêu cầu. Vai trò quan trọng của tỉ lệ mol H2O/Zn trong việc hình thành cấu trúc 3D HP với các lỗ rỗng nguyên vẹn đã được chỉ rõ. Tỉ lệ này góp phần kiểm soát tốc độ của quá trình chín Ostwald và tốc độ khuếch tán ra bên ngoài. Tỉ lệ mol H2O/Zn = 2 được xác định là điều kiện tiên quyết để có được các siêu cầu HP nguyên vẹn. Các siêu cầu này phát xạ mạnh và sắc nét ở 389 nm, cho thấy các ứng dụng quang điện tiềm năng. Ngoài ra, nghiên cứu cũng xem xét việc sử dụng các siêu cầu ZnO HP nguyên vẹn để tổng hợp ZnO cấu trúc 3D dạng hoa có khả năng phân tán ổn định. Quá trình phát triển tinh thể được kiểm soát để xảy ra chủ yếu dọc theo trục c hướng ra ngoài.The synthesis of hollow and porous (HP) ZnO superspheres with intact hollow structures is crucial for various applications, yet it poses significant challenges. This article explores the fundamental aspects of preparing highly crystalline HP ZnO superspheres via a sol-gel process, elucidating the synthetic strategy, formation mechanism, and subsequent utilization for generating pollen-like ZnO superstructures. Under solvothermal conditions at 200°C, employing zinc acetate (0.065 M) in diethylene glycol with varying molar ratios of H2O/Zn, a range of ZnO particles and superspheres were synthesized. Within a molar ratio range of 2 - 4, initial nanoparticles self-assembled into solid and porous (SP) superspheres, evolving dominantly towards or along the c-axis, resulting in HP superspheres with intact hollow structures. Conversely, molar ratios of 6 - 20 yielded only separate nanocrystals instead of superspheres. The critical role of the H2O/Zn molar ratio in forming HP superstructures with intact hollows was highlighted, controlling Ostwald ripening and outward diffusion rates, with a molar ratio of 2 identified as a prerequisite for intact HP superspheres. The resultant intact HP superspheres exhibited intense and sharp band gap emission at 389 nm, indicating potential for optoelectronic applications. Furthermore, the study introduces pollen-like ZnO colloids derived from these intact HP ZnO superspheres, offering stable dispersion. Crystal growth predominantly occurred along the outward-oriented c-axis. The intact HP ZnO superspheres serve as a promising template system for biomimetic pollen-like ZnO superstructures.

1. Đọc trực tuyến

1. Đọc trực tuyến

Tạo bộ sưu tập với mã QR