DFT study on the regeneration mechanism of ZnO surface during the desulfurization of H2S

The regeneration mechanisms of the sulfurized and oxygen-deficient ZnO(101¯0) surfaces in an oxygen atmosphere have been systematically studied by using the density functional theory (DFT) method. An activation energy of 36.79 kJ·mol− 1 is needed for the regeneration of the sulfurized ZnO(101¯0) surface at the GGA–PW91 functional level. The formed SO2 lies on the ZnO(101¯0) surface horizontally, S in SO2 bonds to a surface oxygen atom to form an analogical SO3 structure. Two regeneration mechanisms are studied for the oxygen-deficient ZnO(101¯0) surface. One is that O2 dissociatively adsorbs on the oxygen-deficient ZnO(101¯0) surface leading to the regeneration of the surface. The other is that O2 molecularly adsorbs on the oxygen-deficient ZnO(101¯0) surface, then a little activation energy of 29.43 kJ·mol− 1 is needed to make the surface regenerate. It can be concluded that the sulfurized and oxygen-deficient ZnO(101¯0) surfaces are easy to be regenerated in an atmosphere containing O2.

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► The sulfurized ZnO(101¯0) surface is easy to be regenerated in the presence of O2.
► SO2 prefers to lie on the ZnO(101¯0) surface horizontally.
► The oxygen-deficient ZnO(101¯0) surface can be regenerated easily.