DFT Investigation on the Water Reduction Capacity of 001 Slab model of CdX (X= S, Se, Te) Structures

Theoretical investigation were carried out on the water reduction capacity of slab models of Wurtzite CdS, CdSe and CdTe compounds, which is constructed in the 001 direction. For the systematic study, we are intertwining the relation between energetics of redox reactions and water reduction capacity of materials with the help of Density Functional Theory (DFT) calculations. We found polarization along the c axis of every CdX (X= S, Se, Te) unitcell structures due to the unsymmetrical tetrahedral structure, which leads to charge separation and better photocatalytic activity. Understanding this unique property of this wurtzite CdX structures, we constructed slab models along 001 direction and performed free energy analysis. Our findings reveal the inhibition of Cd-terminated surface for the water reduction reaction whereas all the chalcogenide surfaces provide highly favorable water reduction environment. Further, we also noticed the exciting water reduction capacity of S- terminated surface of CdS structures with a negative energy barrier of -1.28 eV, which is very less compared to all other chalcogenide surfaces