The interaction of H2S with the ZnO(101̄0) surface

Abstract

Using density functional theory with and without Hubbard-U correction we have calculated the geometric structure and the binding energy of H2S molecules adsorbed on the main cleavage plane of ZnO. We find that H2S molecules preferentially dissociate upon adsorption, with a negligible barrier for the first and an activation energy of about 0.5 eV for the second SH bond dissociation. In the low coverage limit of individual molecules single and double dissociation are energetically almost degenerate. At higher coverage double dissociation is favored because of attractive adsorbate-adsorbate interactions. Thermodynamic analysis shows that the double-dissociated state at full saturation with a coverage of 1/2 monolayer is the most stable adsorbate structure for a wide range of temperatures and partial pressures. However, at high H2S chemical potential a full monolayer of single-dissociated H2S becomes thermodynamically more favorable. In addition, at low temperature this structure may exist as a metastable configuration due to the activation barrier for the second SH bond cleavage. Finally we show that it is thermodynamically favorable for adsorbed H2S to react with the first ZnO surface layer to form ZnS and water.

Water aggregation and dissociation on the ZnO(101̄0) surface

“…This observation agrees with recent results for water adsorption on CeO 2 and H 2 S adsorption on ZnO calculated using GGA+U or hybrid DFTs. 89,90 PBE calculates structures and adsorption energies for water on ZnO in good agreement with experiment 44,77 and these properties are not significantly affected by the underestimated band gap. In particular, the trends in relative stability are preserved.…”

ZnO/ZnS (hetero)structures: ab initio investigations of polytypic behavior of mixed ZnO and ZnS compounds

“…In the current work, we have observed similar behavior in the pure ZnS system, where we found wurtzite as the energetically lowest modification while the sphalerite one has a higher energy both on DFT (LDA) and hybrid (HSE) level of approximation, which is in agreement with experimental observations (Gerlach, 1922;Scott & Barnes, 1972;Wells, 1984;Logar et al, 2009;Mardix, 1986;Chao & Gault, 1998;Mardix et al, 1969;Evans & McKnight, 1959;Haussü hl & Mü ller, 1963) and previous calculations (Homann et al, 2006;Engel & Needs, 1990;Boutaiba et al, 2014;Hamad et al, 2009;Goclon & Meyer, 2013;Iversen & Spencer, 2013). In both cases, their energies differ by about 0.004 E h (see Fig.…”

“…This similarity is demonstrated not only on theoretical grounds by the polytype calculations presented here, but also by many experimental observations, such as the existence of wurtzite and sphalerite modifications in both ZnO and ZnS, which are in agreement with the calculations presented in this study. In support of this claim, we would also like to mention recent investigations that suggest the occurrence of theoretically proposed (Zafar et al, 2014;Luo et al, 2017;Goclon & Meyer, 2013;Iversen & Spencer, 2013), synthesized (Skinner & Barton, 1960;Patil et al, 2010;Chen et al, 2008;Shen et al, 2005;Homm et al, 2010;Wang et al, 2015) and natural (Š rot et al, 2003) polymorphs of ZnO intergrown with ZnS, as well as the great amount of research that has been performed on ZnO/ZnS heterostructures and heterojunctions (Wang et al, 2002;Yan & Xue, 2006;Hu et al, 2011;Jia et al, 2013;Sadollahkhani et al, 2014;Daiko et al, 2017;Giri et al, 2014;Tarish et al, 2017;Lu et al, 2009;Tian et al, 2014;Zhu et al, 2008 Sukkabot, 2017;Flores et al, 2018). Taken together, these are strong indications that the synthesis of at least some of the predicted mixed ZnO/ZnS compounds/modifications presented in this study should be possible.…”

Highly Sensitive and Selective H2S Chemical Sensor Based on ZnO Nanomaterial

“…Consequently, the electrical conductance of material was increased. In addition, the H 2 S molecules can adsorb in metastable configurations on the surface of ZnO at relatively high operating temperatures [66]. Therefore, the sulfuration and desulfuration reversible reactions can occur between the H 2 S and ZnO (Equations (3) and (4)).…”