Owing to its high mobility and flexible topology, unmanned aerial vehicles (UAV) are envisioned to play an important role in both civil and military fields to enable agile and ubiquitous connectivity. With the development of the B5G/6G communication technologies, the demand for wireless communication services is experiencing a significant increase. Consequently, the spectrum resources are becoming increasingly scarce. However, almost existing full-duplex UAV networking schemes still use the centralized architecture, which is fragile in the circumstances where communication conditions are unpleasant. Thus motivated, we propose a novel decentralized full-duplex UAV ad-hoc network architecture to improve its invulnerability and spectrum efficiency. Then we design the efficient clustering and multiple access protocols respectively under the full-duplex pattern to improve the packet transmission rate and reduce the decentralized network access time effectively. We also conduct a preliminary simulation study to validate the feasibility of the adopted architecture. Finally, we explore the primary challenges and potential avenues for the decentralized full-duplex UAV adhoc networks in conjunction with other cutting-edge technologies.