Developing catalysts with high activity and high selectivity toward methanol, and elucidating the structure-activity relationship, are important in the area of CO2 hydrogenation. Herein, a simple ultrasonic-assisted impregnation modification method, which modifies a CuZnZr catalyst for methanol synthesis from CO2, is reported. The results show high methanol selectivity (97.1%) and a CO2 conversion of 10.7%, in the presence of the catalyst modified with CuBr2 (CuZnZr/CuBr2). Furthermore, detailed investigations of the structure-activity relationship demonstrate that the CuBr2 modification influences both the catalyst surface properties and catalyst morphology. In particular, residual Br, as a CuBr phase, is stabilized on the catalyst surface and is able to significantly passivate the reverse water-gas shift activity on the Cu surface; therefore, CO formation on the Cu surface is almost completely suppressed. The catalytic evaluation and IR data support the formate pathway mechanism in the presence of the CuZnZr/CuBr2 catalyst to synthesize methanol from CO2. (C) 2020 Elsevier Inc. All rights reserved.