One-Step Synthesis of Ag–Cu Bimetallic Nanoparticles on p-Si Photoelectrodes for Solar-Driven CO₂ Reduction

Abstract

In the present work, we report the one-step synthesis of Ag x Cu100–x bimetallic nanoparticles (NPs) on p-type silicon (p-Si) supports and their application as photocathodes for the photoelectrochemical CO2 reduction reaction (PEC-CO2RR). Based on the metal-assisted chemical etching (MACE) of Si in HF medium, the proposed method allows the formation of NPs homogeneously distributed on the Si surface, with an excellent control of their bimetallic composition, surface coverage, and morphology by adjusting the experimental conditions (deposition time, precursor concentrations). Microstructural studies reveal a phase-separated polycrystalline structure for the bimetallic with a high dispersion of Ag and Cu nanocrystallites, remarkable for Ag/Cu nanostructures synthesized by soft chemistry. The analysis of the PEC-CO2RR shows a better performance of Ag50Cu50/p-Si than Ag/p-Si and Cu/p-Si, with an onset potential shift of 840 mV and a ratiometric power saved of ∼3% compared to an analogous metal electrode in CO2 saturated 0.5 M NaHCO3. Photoelectrolysis tests under 1 sun illumination coupled with gas chromatography demonstrate the capacity of the bimetallic photocathode to guide the selectivity with the applied potential. Thus, CO2 conversion to CO and CH4 is achieved on Ag50Cu50/p-Si, with a maximum Faradaic efficiency (FE) of 26% and 18.2% at −0.72 and −0.87 VRHE, respectively. These values are consistent with recent research on Ag–Cu systems on Si for the PEC-CO2RR but are obtained at significantly lower overpotentials. These are the first results ever reported for the PEC-CO2RR on p-Si photocathodes decorated with AgCu NPs. The proposed deposition method is inexpensive, easily scalable, and can be extended to any bimetallic system whose elements are compatible with MACE of Si.

Ag‐Based Bimetallic Nanoparticles for the Catalytic Reduction of Nitrophenol and Organic Dyes: An Overview

“… SEM images of (a) Ag nanoparticles Reproduced from Ref [164] . Copyright©2020, Elsevier B.V (b) Ag−Cu nanoparticles Reproduced from Ref [184] . Copyright© 2023, American Chemical Society(c) Cu nanoparticles Reproduced from Ref [185] .…”

“…[164] Copyright©2020, Elsevier B.V (b) AgÀ Cu nanoparticles Reproduced from Ref. [184] Copyright© 2023, American Chemical Society(c) Cu nanoparticles Reproduced from Ref. [185] with permission from the Royal Society of Chemistry.…”

Photoelectrocatalytic Utilization of CO2: A Big Show of Si‐based Photoelectrodes

“…[39] It is worth mentioning that AgÀ Cu bimetallic nano-nanoparticles modified p-Si photocathode was developed and used for PEC reduction of CO 2 . [40] Graphene as a new type of electrocatalyst also has outstanding performance in the PEC reduction of CO 2 . Yang et al used N-doped graphene quantum sheets (N-GQSs) as heterogeneous electrocatalysts to modify p-type Si nanowires, achieving a Faraday efficiency of up to 95 % for PEC reduction of CO 2 to CO at a low potential.…”

Au-decorated Sb2Se3 photocathodes for solar-driven CO2 reduction

“…Recent advances in PEC CO 2 RR have shown that different products are possible depending on the cocatalyst used. [27][28][29] The most commonly used cocatalysts are Au, [30][31][32][33][34][35][36] Cu, [37][38][39] Ag, [39][40][41] and different molecular catalysts. [42][43][44][45] Aside from choosing the appropriate cocatalyst, it was reported that tuning the interface exposed to the electrolyte can also have an impact by stabilizing the reaction intermediate (i.e., *COOH from CO 2 ), which can lead to lower overpotential and higher Faradaic efficiency.…”