Convergence of blockchain and artificial intelligence in IoT network for the sustainable smart city

•A study on convergence of Blockchain-AI for sustainable smart city.•Presents the security issues and challenges based on various dimensions.•Discusses the blockchain security enhancement solutions, and summarizing key points.•Summarize the open issues and research direction: new security suggestions, future guidelines.In the digital era, the smart city can become an intelligent society by utilizing advances in emerging technologies. Specifically, the rapid adoption of blockchain technology has led a paradigm shift to a new digital smart city ecosystem. A broad spectrum of blockchain applications promise solutions for problems in areas ranging from risk management and financial services to cryptocurrency, and from the Internet of Things (IoT) to public and social services. Furthermore, the convergence of Artificial Intelligence (AI) and blockchain technology is revolutionizing the smart city network architecture to build sustainable ecosystems. However, these advancements in technologies bring both opportunities and challenges when it comes to achieving the goals of creating a sustainable smart cities. This paper provides a comprehensive literature review of the security issues and problems that impact the deployment of blockchain systems in smart cities. This work presents a detailed discussion of several key factors for the convergence of Blockchain and AI technologies that will help form a sustainable smart society. We discuss blockchain security enhancement solutions, summarizing the key points that can be used for developing various blockchain-AI based intelligent transportation systems. Also, we discuss the issues that remain open and our future research direction, this includes new security suggestions and future guidelines for a sustainable smart city ecosystem