Remarkable Influence of α-SnWO₄ Exposed Facets on Their Photocatalytic Performance for H₂ and O₂ Evolution Reactions

Abstract

A significant effect of the five major (121), ( 210), ( 111), (200), and (040) exposed facets obtained experimentally for orthorhombic -SnWO 4 material on its performance for photocatalytic water splitting is highlighted from a hybrid DFT-based comprehensive study.Their electronic, redox, and transport characteristics reveal significant anisotropic characters.The specific function of each surface in water oxidation and proton reduction is in direct relationship with the exposed W coordination number. Our study predicts the (210) facet as being the only possible good candidate for OER and HER upon surface modification, whereas the (200) facet is found a good candidate only for HER. The (121) facet is an acceptable candidate for both OER and HER and the (111) facet for HER only but less potentials than ( 210) and ( 200). The (040) facet is an unsuitable candidate neither for OER nor for HER. Interestingly, the proposed (001) facet is predicted to be the best candidate for HER. These results indicate the right direction to be followed for enhanced photocatalytic water splitting reactions based on a rational design of facet-oriented -SnWO 4 samples.

Need for Rationally Designed SnWO4 Photo(electro)catalysts to Overcome the Performance Limitations for O2 and H2 Evolution Reactions

“…Very recently, we examined the fundamental characteristics of the five main (210), (121), (040), (200), and (111) facets obtained in synthesized α-SnWO 4 samples. − The two experimental (040) and (200) facets are identical to the (010) and (100) ones. The two (210) and (121) facets are made of three-coordinated Sn with four- and five-coordinated W, respectively.…”

“…Comparison with the Main Facets of Synthesized α-SnWO 4 Samples. Very recently, 64 we examined the fundamental characteristics of the five main (210), ( 121), (040), (200), and (111) facets obtained in synthesized α-SnWO 4 samples. 28−34 The two experimental (040) and ( 200 Interestingly, the similar behavior in the W exposed species coordination number between the (111), (100), and (001) facets as well as in the exposed W coordination number between (121) and (210) facets led to a similarity in the electronic and redox characteristics.…”

Nail-like α-SnWO4 Array Film with Increased Reactive Facets for Photoelectrochemical Water Splitting

“…Zhu et al converted WO 3 particle films to form α-SnWO 4 porous films with a photocurrent of ∼100 μA/cm 2 (1.23 V vs RHE). The above PEC performance is far below the theoretical value (24.4 mA/cm 2 ), which has been assumed to be the poor carrier transport that limits the photogenerated holes arriving at the material surface …”

The surface reconstruction induced enhancement of the oxygen evolution reaction on α-SnWO4 (010) based on a density functional theory study

“…Hence, it has become an appealing option over the past few years. Theoretically, Harb et al 14 studied five significant (121), (210), (111), (200), and (040) exposed facets obtained experimentally from a-SnWO 4 using DFT. They found that the (210) and (121) facets are ideal candidates for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), whereas the (200) and (111) facets are only active for the HER.…”