  Web 3.0 is the next-generation Internet that enables participants to read,
write, and own contents in a decentralized manner. It is mainly driven by
blockchain, semantic communication, edge computing, and artificial
intelligence, which can construct value networks to achieve participatory
economics based on participatory decision making. Web 3.0 can capture the
characteristics of blockchain, semantic extraction, and communication to
achieve decentralized semantic sharing and transfer information precisely.
However, current Web 3.0 solutions focus on the blockchain while overlooking
other new technologies' roles in Web 3.0. To further unleash the advantages of
semantic extraction and communication in Web 3.0, in this paper, we propose a
blockchain-based semantic exchange framework to realize fair and efficient
interactions. In this framework, we first attempt to tokenize semantic
information into Non-Fungible Token (NFT) for semantic exchange. Then we
utilize a Stackelberg game to maximize buying and pricing strategies for
semantic trading. We also leverage Zero-Knowledge Proof to share authentic
semantic information without publishing it before receiving payments, which can
achieve a fair and privacy-preserving trading compared with current NFT
marketplaces. A case study about urban planning is given to show clearly the
proposed mechanisms. Finally, several challenges and opportunities are
identified.
