VNU Journal of Science Mathematics – Physics, Vol 37, No 3 (2021) 42 50 42 Original Article Dependence of Hydrothermal Time on Structural Characteristics and Photocatalytic Properties of SnO2 Nanoparticles Pham Van Tuan1,*, Le Trung Hieu1, Vu Thi Tan2, Hoang Ba Tuong2, Tran Thi Quynh Hoa3, Nguyen Xuan Sang4, Tran Ngoc Khiem1 1International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, 1 Dai Co Viet, Hanoi, Vietnam 2School of Chemical Engineering,[.]