Enhanced charge-carrier dynamics and efficient solar-to-urea conversion on Si-based photocathodes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38349884.
- Also identified by DOI 10.1073/pnas.2311326121 and PMC identifier 10895350.
- Licence recorded as CC BY-NC-ND.
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Abstract
Photoelectrochemical (PEC) coupling of CO<sub>2</sub> and nitrate can provide a useful and green source of urea, but the process is affected by the photocathodes with poor charge-carrier dynamics and low conversion efficiency. Here, a NiFe diatomic catalysts/TiO<sub>2</sub> layer/nanostructured n<sup>+</sup>p-Si photocathode is rationally designed, achieving a good charge-separation efficiency of 78.8% and charge-injection efficiency of 56.9% in the process of PEC urea synthesis. Compared with the electrocatalytic urea synthesis by using the same catalysts, the Si-based photocathode shows a similar urea yield rate (81.1 mg·h<sup>-1</sup>·cm<sup>-2</sup>) with a higher faradic efficiency (24.2%, almost twice than the electrocatalysis) at a lower applied potential under 1 sun illumination, meaning that a lower energy-consumption method acquires more aimed productions. Integrating the PEC measurements and characterization results, the synergistic effect of hierarchical structure is the dominating factor for enhancing the charge-carrier separation, transfer, and injection by the matched band structure and favorable electron-migration channels. This work provides a direct and efficient route of solar-to-urea conversion.