There are a plenty amount of topics because the sustainability concept refers to sustainable governance, civic culture, Mobility, Economy and so on. It really depends on your interests. My advice is that study the following book to choose your topics:
McKinnon, A., Cullinane, S., Browne, M., & Whiteing, A. (2015). Green Logistics: Improving the environmental sustainability of logistics.
You can analyze the impact on emissions generated, cost associated and resource efficiency through different models of supply chain regarding circular economy.
Now a days best topic for research is development of performance measurement system for sustainable supply chain management with environmental management.
I reccommend you all titles from EcoProduction Book Series (Environmental Issues in Logistics and Manufacturing) https://www.springer.com/series/10152?detailsPage=titles.
The SARS-CoV-2 (Covid-19) coronavirus pandemic in 2020 caused temporary disruptions and the permanent shortening and simplification of international intermodal supply and sourcing chains. As part of the changes in supply and supply logistics taking place in this regard, it is possible to increase the scale of implementation of the sustainable development goals in this area, i.e. the development of sustainable supply and supply chains. Therefore, I propose a research topic that will combine the various above-mentioned aspects and determinants of development and analysis of the effectiveness of sustainable supply and supply chains.