Stabilizing an ultrathin MoS₂ layer during electrocatalytic hydrogen evolution with a crystalline SnO₂ underlayer

Abstract

A molybdenum disulfide coating deposited on a macroporous substrate as an electrocatalyst is mobile on an underlying amorphous tin dioxide substrate, but remains continuous and impervious to acidic conditions on crystalline tin dioxide.

Structural Aspects of MoSx Prepared by Atomic Layer Deposition for Hydrogen Evolution Reaction

“…The activities of our a-MoS 2+ x catalysts (η 10mA/cm2 = 208–246 mV) are comparable to those reported for a-MoS 2+ x electrocatalysts on flat substrates, despite our catalyst loadings being significantly lower compared to the majority of the literature (Table S8 in the Supporting Information). ,,− ,,,− Although a few reports of a-MoS 2+ x catalysts with η 10mA/cm2 below 200 mV exist, these values have been achieved using loadings at least 50 times higher than those in the present study ,,, or high surface area substrates. ,, As the MoS x catalysts can be or become porous, , high loadings can increase the activity per geometric area. The comparable or even superior inherent (per atom) activity of our a-MoS 2+ x combined with the capability of PEALD to deposit conformal films on nanostructured substrates enables significant improvements in activity per geometric area toward practical electrolyzers. , Compared to the thick film or particle form catalysts, our PEALD thin film catalysts lend themselves well to obtaining insights into catalytic activity and stability as described below.…”

“…The activities of our a-MoS 2+ x catalysts (η 10mA/cm2 = 208–246 mV) are comparable to those reported for a-MoS 2+ x electrocatalysts on flat substrates, despite our catalyst loadings being significantly lower compared to the majority of the literature ( Table S8 in the Supporting Information). 26 , 27 , 33 − 36 , 42 , 43 , 65 − 70 Although a few reports of a-MoS 2+ x catalysts with η 10mA/cm2 below 200 mV exist, these values have been achieved using loadings at least 50 times higher than those in the present study 7 , 8 , 29 , 30 or high surface area substrates. 35 , 38 , 68 As the MoS x catalysts can be or become porous, 30 , 71 high loadings can increase the activity per geometric area.…”

Synthesis of In-Plane Oriented Tin Sulfides by Organosulfur-Mediated Sulfurization of Ultrathin SnO2 Films

“…can be finely tuned to target the desired sulfide phase and grain size. Morever, such an approach could facilitate the formation of SnS x /SnO 2 heterostructures where SnO 2 can directly serve as transparent electrode for contacting SnS x . But so far, the few studies conducted on sulfurization of SnO 2 layers were limited to the use of the highly toxic H 2 S or low volatility elemental sulfur and either display limited kinetic or require high temperatures (550 °C) with the formation of mixed tin sulfide phases …”

“…Morever, such an approach could facilitate the formation of SnS x /SnO 2 heterostructures where SnO 2 can directly serve as transparent electrode for contacting SnS x . 53 But so far, the few studies conducted on sulfurization of SnO 2 layers were limited to the use of the highly toxic H 2 S or low volatility elemental sulfur and either display limited kinetic 50 or require high temperatures (550 °C) with the formation of mixed tin sulfide phases. 54 In this study, we investigate the use of volatile and nontoxic organosulfur molecules, namely tert-butylthiol (TBT) and tertbutyl disulfide (TBDS) (see Figure 1), as a safe and convenient alternative to H 2 S and elemental sulfur to convert selectively ALD-deposited SnO 2 thin films into SnS or SnS 2 .…”