1. Type-I Heterojunctions: Both the conduction band minimum (CBM) and valence band maximum (VBM) of one semiconductor are higher than those of the other. This alignment is less effective for charge separation but can be useful for certain applications where charge transfer is not critical.
2. Type-II Heterojunctions: The CBM of one semiconductor is lower, and the VBM is higher than those of the other semiconductor. This staggered alignment is ideal for charge separation, making Type-II heterojunctions highly effective for photocatalytic and electrocatalytic applications.
3. Type-III Heterojunctions: Both the CBM and VBM of one semiconductor are either higher or lower than those of the other semiconductor. This type is less common in catalytic applications due to its inefficient charge separation properties.
