Prof. Ren and the WET (Water & Energy Technologies) lab members work on Water-Energy Nexus especially in areas of water sector decarbonization and resource recovery during environmental and chemical processes such as water and CO2 electrolysis, wastewater treatment and reuse, water desalination, remediation, and carbon capture and utilization. They use electrochemistry, microbiology, AI/machining learning and system engineering tools to understand the fundamental determinant factors of the systems so as to enhance design, operation, and monitoring in concert with traditional approaches. Prof. Ren collaborates with colleagues from different disciplines. The group has been funded by federal and state agencies as well as private sponsors and published papers in Nature Sustainability, Nature Climate Change, Nature Energy, Science Advances, Energy & Environmental Science, Environmental Science & Technology, Water Research, and other journals. Prof. Ren co-founded 2 companies with students to translate research findings into real-world applications.