Example of direct chemoreceptors are:
Olfactory receptor neuron.
Taste buds.
Vomeronasal organ.
All of the above.
Chemoreceptor (Chemosensor) is a sensory receptor that transduces a chemical signal into an action potential. There are two main classes of chemosensor.
a) Direct:
Taste buds are direct chemoreceptors. Aqueous chemical compounds come into contact with chemoreceptors in the mouth such as taste buds on the tongue and trigger responses.
b) Distant: 
Olfactory receptor neurons in the olfactory system. The main olfactory epithelium (MOE) and the Vomeronasal organ (VNO) detects odorants and pheromones respectively.