Editors’ Choice—Review—Creating Electrocatalytic Heterojunctions for Efficient Photoelectrochemical CO₂ Reduction to Chemical Fuels

Abstract

Artificial photosynthesis can potentially address the global energy challenges and environmental issues caused by fossil fuels. Photoelectrochemical heterojunction structures of new photonic structures have been developed for efficient sunlight absorption, charge generation and separation and transport, and selective reduction of CO2 and water splitting. In this review, an overview of several recently developed heterojunction model systems comprised of low-cost photonic materials such as transition metal dichalcogenides (TMDs), perovskite semiconductor nanocrystals, and plasmonic nanostructures is presented to rationalize the potential benefits of utilizing heterojunction structures for efficient and selective CO2 reduction with renewable energy resources. Recent advances in electroanalytical methods for CO2 reduction such as scanning electrochemical microscopy (SECM) are reviewed. These techniques can potentially resolve local CO2 reduction kinetics and their spatial heterogeneities of a heterojunction photoelectrochemical structure.

Decoupling the Impacts of Engineering Defects and Band Gap Alignment Mechanism on the Catalytic Performance of Holey 2D CeO2−x‐Based Heterojunctions

“…Heterojunction nanostructures increasingly have become important owing to their advantageous properties in many technological areas, including thermocatalysis, electrocatalysis, photocatalysis, and photovoltaics. [1][2][3][4][5] In catalytic applications, heterojunction nanostructures leverage defect engineering as well as surface, structural, and morphological characteristics in order to enhance the performance owing to the synergism between the materials. The importance of nanoscale architecture has been highlighted by the recent emergence of the outstanding catalytic performance of nanosheets of various systems owing to the high densities of active sites deriving from their high surface areas.…”

The origins of charge separation in anisotropic facet photocatalysts investigated through first-principles calculations

“…Then, the macroscopic average electrostatic potential (MAEP) V is the average ofṼ (z) over one period with the period length p: Finally, the CBO and VBO of a junction A/B can be determined by eqn (3). The rst two terms describe the band discontinuity across the interface between materials A and B lattice segments, and the last term is the band lineup at the interface.…”

“…To enhance the charge separation efficiency, previous strategies include: (1) combining the photocatalyst with a cocatalyst to form a p-n heterojunction and introduce a built-in potential on the photocatalyst surface to promote charge separation during photocatalysis. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] For instance, Afshar et al put p-type tetrahexahedron-SrTiO 3 cocatalyst on n-type TiO 2 to form a heterojunction to improve the efficiency of the photocatalytic reaction. 17 (2) Introducing different types of defects in photocatalyst crystals to control the distribution of surface photogenerated charges and resulting charge separation.…”

Differentiating Defects and Their Influence on Hematite Photoanodes Using X-ray Absorption Spectroscopy and Raman Microscopy

“…Photoanodes for the oxygen evolution reaction (OER) are arguably the most widely studied photoelectrodes for PEC reactions. They are critical in solar fuel schemes because they provide the electrons and protons required by the cathodic reactions such as hydrogen evolution, CO 2 reduction, and N 2 reduction. − Numerous photoanode materials are studied for OER, but hematite (α-Fe 2 O 3 ) remains one of the most intensely studied options. Hematite offers an earth-abundant composition, a near ideal band gap of 2.1 eV, and a theoretical maximum value 12.5 mA cm –2 . , Hematite also stands out because the maximum attained photocurrent density, the onset of photoelectrocatalysis, the shape of current–voltage response, and surface reaction kinetics all exhibit significant variation across the literature.…”