Abstract: A blockchain-based AI model training method is provided, comprising: building an original AI model according to features of data sets; randomly allocating participants in a training process proportionally into three categories: a model trainer, a model verifier and a model uploader, prior to start of each round of training of the original AI model; during each round of training, generating, by the model trainer and the model verifier, respective partial models of a current round; checking, by the model verifier, partial models generated by the model trainer through using partial models generated locally; aggregating, by the model uploader, all partial models passing the checking of the model verifier to obtain a global model of the current round, and packing the global model, checking results and all the partial models of the current round into a blockchain.

Abstract: Disclosed is a metal-semiconductor contact structure based on two-dimensional (2D) semimetal electrodes, including a semiconductor module and a metal electrode module, where the semiconductor module is a 2D semiconductor material, and the metal electrode module is a 2D semimetal material with no dangling bonds on its surface; the 2D semiconductor material and the 2D semimetal material are interfaced with a Van der Waals interface with a surface roughness of 0.01-1 nanometer (nm) and no dangling bonds on the surface, the 2D semiconductor material and the 2D semimetal material are spaced less than 1 nm apart.