Modulating Charge Carrier Dynamics among Anisotropic Crystal Facets of Cu₂O for Enhanced CO₂ Photoreduction

Abstract

Photogenerated charge separation is a crucial factor determining the enhancement in the energy efficiency of photocatalysts. In this work, through computational simulations of Cu2O crystals with different facets, edge-truncated cubic Cu2O was confirmed to enable efficient charge separation. To verify the computational predictions, Cu2O photocatalysts with two different morphologies and facet orientations, i.e., cubic and edge-truncated cubic structures, were synthesized and characterized. The photocatalytic activity toward the selective reduction of CO2 to methanol on the edge-truncated cubic Cu2O with anisotropic {100} and {110} facets was found to be nearly 5.5-fold higher than that of cubic Cu2O with only {100} facets. This observed difference is ascribed to the effective separation and migration of photogenerated charge carriers as well as the selective accumulation of electrons and holes on different facets of edge-truncated cubic Cu2O crystals. The effects of work function differences between {110} and {100} facets on the electronic band structure and anisotropic charge separation were also identified. These findings provide important guidelines for the design and synthesis of highly efficient and well-defined photocatalysts for CO2 conversion to fuel.

A Review on Cu2O-Based Composites in Photocatalysis: Synthesis, Modification, and Applications

“…The electronic density of the Cu active sit surface moved from Cu (i) to Cu (ii), and the oxidation state of the Cu chan (ii) to Cu (i) after CO2 conversion under light. In 2022, Sahu et al [74] syn characterized Cu2O photocatalysts with cubic and truncated cubic structure spondingly exposed crystal faces were different (Figure 8). Due to the selec lation of e − and h + on different crystal planes, the photocatalytic activity in ducing CO2 to methanol on cubic Cu2O with anisotropic {100} and {110} cryst nearly 5.5 times higher than that on cubic Cu2O with only {100} crystal plan Meanwhile, researchers have adopted various modification methods to structure and performance of the photocatalyst.…”

Advances in CO2 utilization employing anisotropic nanomaterials as catalysts: a review

“…According to the findings of computational simulations that Kumar Sahu et al conducted on Cu 2 O crystals with various facets, edge-truncated cubic Cu 2 O showed to permit effective charge separation ( Kumar Sahu et al, 2022 ). Cu 2 O photocatalysts having two separate morphologies and facet alignments, namely, cubic and edge-truncated cubic structures, were prepared and studied in order to validate the computational predictions ( Figure 10 ).…”

Nanocomposites of Cu2O with plasmonic metals (Au, Ag): design, synthesis, and photocatalytic applications

“…15–19 The type of exposed crystal facets in Cu 2 O nanostructures has been shown to affect their photocatalytic behavior. 20,21 Thus, modification of their photocatalytic properties can be readily achieved through careful morphological control.…”