What question did this study set out to answer?

The research aims to understand how a Re bipyridyl catalyst can be effectively attached to p-Si(111) and its implications for CO2 reduction.

April 24, 2026

Insights on Covalent Attachment of a Re Bipyridyl Catalyst onto p -Si(111) Using an Alkyl Linker for Photoelectrochemical CO 2 Reduction

Key Points

The research aims to understand how a Re bipyridyl catalyst can be effectively attached to p-Si(111) and its implications for CO2 reduction.
Covalent attachment of the catalyst was achieved using an organolithium route.
Cyclic voltammetry (CV) was employed to examine the electronic properties and reactivity.
DFT geometry optimizations were carried out to predict catalyst behavior under various conditions.
The Re bipyridyl catalyst showed two single-electron reductions with photovoltages of 320 mV and 400 mV.
Faradaic efficiencies of 15% for CO and 54% for H2 were achieved under controlled-potential electrolysis.
A kinetic barrier was identified as influencing the selectivity shift towards hydrogen evolution reaction.

Abstract

Re(bpy)(CO)3Cl with a hexyl chain linker was covalently attached to p-type Si(111) via Si-C bond using an organolithium route and confirmed by XPS and ATR-FTIR. Cyclic voltammetry (CV) shows two single-electron reductions with estimated photovoltages of 320 mV and 400 mV for the first and second reductions, respectively. Both reductions were shifted by approximately 200 mV to more positive potentials relative to the homogeneous analogue measured with a methyl-terminated p-type Si(111). CV in a concentrated Cl- solution indicated that the reformation of the Re-Cl bond is slow, indicating a kinetic barrier in reactivity at the active site. DFT geometry optimizations suggest that under negative bias the complex preferentially adopts configurations that move farther from the methylated Si surface, with the Re-Cl bond oriented parallel to it. Under CO2, only slight catalytic current enhancement was observed. Controlled-potential electrolysis (CPE) at -2.3 V vs Fc+/0 yielded Faradaic efficiencies (FEs) of 15% for CO and 54% for H2, compared to ∼100% FE for CO observed in the homogeneous system. The selectivity shift is best explained by the dominance of HER at the native Si surface, while CO formation remains limited by slow EC kinetics at the active site of the immobilized Re complex.

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Cite This Study

Lee et al. (Tue,) studied this question.

synapsesocial.com/papers/69eb0803553a5433e34b347a https://doi.org/https://doi.org/10.1021/acs.inorgchem.6c01231

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