Open AccessDesigning catalysts for water splitting based on electronic structure considerations
Author(s) -
Sara Abdel Razek,
Melissa R. Popeil,
Linda Wangoh,
Jatinkumar Rana,
Nuwanthi Suwandaratne,
Justin L. Andrews,
D. J. Watson,
Sarbajit Banerjee,
Louis F. J. Piper
Publication year - 2020
Publication title -
electronic structure
Language(s) - English
Resource type - Journals
ISSN - 2516-1075
DOI - 10.1088/2516-1075/ab7d86
Subject(s) - water splitting , lone pair , density functional theory , electronic structure , photocatalytic water splitting , band gap , quantum dot , chemical physics , nanowire , materials science , catalysis , chemistry , nanotechnology , photocatalysis , computational chemistry , optoelectronics , molecule , biochemistry , organic chemistry
The disproportionation of H 2 O into solar fuels H 2 and O 2 , or water splitting, is a promising strategy for clean energy harvesting and storage but requires the concerted action of absorption of photons, separation of excitons, charge diffusion to catalytic sites and catalysis of redox processes. It is increasingly evident that the rational design of photocatalysts for efficient water splitting must employ hybrid systems, where the different components perform light harvesting, charge separation and catalysis in tandem. In this topical review, we report on the recent development of a new class of hybrid photocatalysts that employs M x V 2 O 5 (M = p-block cation) nanowires in order to engineer efficient charge transfer from the photoactive chalcogenide quantum dots (QDs) to the water-splitting and hydrogen evolving catalysts. Herein, we summarize the oxygen-mediated lone pair mechanism used to modulate the energy level and orbital character of mid-gap states in the M x V 2 O 5 nanowires. The electronic structure of M x V 2 O 5 is discussed in terms of density functional theory and hard x-ray photoelectron spectroscopy (HAXPES) measurements. The principles of HAXPES are explained within the context of its unique sensitivity to metal 5(6)s orbitals and ability to non-destructively study buried interface alignments of quantum dot decorated nanowires i.e., M x V 2 O 5 /CdX (X = S, Se, Te). We illustrate with examples how the M x V 2 O 5 /CdX band alignments can be rationally engineered for ultra-fast charge-transfer of photogenerated holes from the quantum dot to the nanowires; thereby suppressing anodic photo-corrosion in the CdX QDs and enabling efficacious hydrogen evolution.