Tuning Selectivity of Photoelectrochemical Water Oxidation via Facet-Engineered Interfacial Energetics

Abstract

Water oxidation kinetics has been identified as the bottleneck of the solar water splitting reaction for H2 production. Herein, we demonstrate that even for crystal facets with the same thermodynamically favorable pathway for water oxidation, the interfacial energetics formed by the terminated facet/electrolyte interface can significantly regulate the water oxidation kinetics to tune the product selectivity. Specifically, we elucidate that the (010) facet of the BiVO4 photoanode can offer suitable band bending and deep valence band level to produce high-value-added hydrogen peroxide (H2O2) with an average Faradaic efficiency of 70% from water oxidation. This simple strategy without other modifications can lead to a 30-fold increase in the applied bias photon-to-current efficiency of photoelectrochemical water splitting. This study sheds new light on the crystal facet effect beyond the erstwhile focus on charge separation and transfer and offers a new opportunity to enhance the solar-to-H2 efficiency.

Piezocatalytic and Photocatalytic Hydrogen Peroxide Evolution of Sulfide Solid Solution Nano‐Branches from Pure Water and Air

“…Therefore, it is thermodynamically feasible to produce H 2 O 2 by the sequential two‐step single‐electron indirect reaction. [ 52–54 ]…”

Engineering Nonprecious Metal Oxides Electrocatalysts for Two‐Electron Water Oxidation to H2O2

“…discovered that the exposed facet is vital to the kinetic of 2e‐WOR for BiVO 4 ( Figure 13 ). [ 118 ] As shown in Figure 13a–c, three kinds of BiVO 4 exposed with different morphologies of cuboid, truncated pyramid, and quasi‐pyramid shapes were prepared. It is worth noting that these prepared BiVO 4 are not perfect microcrystals, two different facets of (010) and (110) are combined or squeezed with each other, the same adjacent angles of 66° exists between (010) and (110) facets.…”

“…Moreover, under the photoelectrochemical conditions, coating SnO 2−x can further reduce the band bending of the BiVO 4 to convert 2e/4e WOR to 1e/2e reaction, such that a high FE of 86% for H 2 O 2 generation can be achieved. [118] Copyright 2021, American Chemical Society.…”

“…h) Summary of the average or maximum FE of 2e-WOR for H 2 O 2 production over different nonprecious catalysts. Reproduced with permission [118]. Copyright 2021, American Chemical Society.…”

Enhanced charge collection and surface activity of a CuBi2O4 photocathode via crystal facet engineering

“…Crystal facet engineering, which modulates the preferred orientation and selective exposure of higher activity facets, is an emerging approach to enhance the charge collection and surface activity of photoelectrodes. [23][24][25] For instance, a bismuth vanadate lm with a preferred [001] orientation and exposed (001) facets has been reported to exhibit excellent intrinsic charge transport properties and surface activity. [26][27][28] Successful design of crystal engineering depends on in-depth understanding of the specic semiconductor's surface tension and catalytical activity.…”