Mixed-dimensional binary heterostructures, especially 0D/2D heterostructures, have attracted significant attention due to their unique physical properties. In this contribution, 0D bismuth quantum dots (Bi QDs, VA) are immobilized onto 2D Te nanosheets (Te NSs, VIA) to prepare Bi QDs/Te NSs binary heterostructures (Bi/Te) through a facile and cost-effective hydrothermal method. The results from both experiments and density functional theory (DFT) calculations demonstrate the enhanced photo-response behaviors of Bi/Te-based photoelectrochemical (PEC)-type photodetectors (PDs). The as-prepared PDs exhibit a high photocurrent of 18.21 μA cm-2, significantly higher than those of previously reported pristine Bi QD and Te NS-based PDs. The PDs are further demonstrated to have excellent self-power capability and long-term stability over 30 days. Additionally, the obtained 786 fs pulse output signal in the telecommunications band reveals the great potential of Bi/Te for ultrafast photonic devices. It is believed that such VA/VIA binary heterostructures provide opportunities for developing multifunctional optoelectronic devices for nano-science applications.