DOI: 10.5061/dryad.d7wm37qbc
title: Using waste CO2 to produce essential amino acids for humans: An efficient photoelectrochemical route

description: L-Phenylalanine (L-Phe), an essential amino acid for humans, is widely
 used as building blocks. Currently, L-Phe is obtained via biosynthetic
 methods including microbial and enzymatic processes, but their tightly
 complex feedback regulation and lengthy reaction steps lead to a low
 practical yield of L-Phe. Here, we have designed a hierarchical Si-based
 photocathode for L-Phe synthesis by photoelectrochemical coupling of waste
 CO2 and nitrophenyl ethane, achieving a high yield rate of 37.5
 μg·h-1·cm-2 and a remarkable faradaic efficiency of 21.2% at low applied
 potential under 1 sun illumination. The hierarchical structure with
 CuO-TiO2-C mixtures dispersed in amorphous TiO2 layer/n+p-Si creates an
 internal built-in electric field and forms plentiful conducting channels
 to efficiently realize the injection of electrons into Cu and Ti sites.
 These Cu and Ti sites adsorb and activate the CO2 and nitrophenyl ethane,
 respectively, cooperatively facilitating the L-Phe synthesis. This work
 introduces an environmentally friendly, and highly efficient approach for
 converting solar energy into valuable amino acid products.
description: The dataset was collected by photoelectrochemical test and
 physical characterization of catalysts.
description: # Using waste CO2 to produce essential amino acids for humans: An
 efficient photoelectrochemical route
 [https://doi.org/10.5061/dryad.d7wm37qbc](https://doi.org/10.5061/dryad.d7wm37qbc) ## Description of the data and file structure  All data generated or analyzed during this study are included in this Article (and Supplementary Information). Data for Figs. 1–5 is available as source data with this paper The Data consists of the data of Figures (from Figure 1 to Figure 5) Figure 1 includes XRD patterns of TiO2 NPs, CuO NPs, TiO2/Si and CTC/TiO2/Si. XPS spectra of CTC/TiO2/Si, Ti 2p and Cu 2p. Figure 2 includes L-Phe yield rate and FE of CTC/TiO2/Si measured at various potentials in a CO2-saturated 0.5 M PBS-0.01 M nitrophenyl ethane-3 vol% tetrahydrofuran electrolyte for 1 h. 1H NMR spectra of post-electrolysis electrolytes on CTC/TiO2/Si at -0.5 V *vs* RHE with different PEC reaction time. Right inset: Magnified spectra of the marked area to reveal the 1H NMR signal of L-Phe. Left inset: Corresponding L-Phe concentration in the reacted electrolytes by the calibration curve from standard solutions of L-Phe with known concentrations. The fitting curve shows good linear relation of NMR peak intensity with L-Phe concentration (*y* = 0.3806*x* + 0.0057, *R*2 = 0.999). Potential-dependent product distributions in 1-h PEC reaction of CTC/TiO2/Si. Time-dependent L-Phe yield and FE obtained on CTC/TiO2/Si at -0.5 V *vs* RHE. Figure 3 includes the surface potential as a function of testing time on CuO-TiO2-C cocatalysts via chopping the light. The internal electric field of CTC/TiO2/Si in the PEC process with single CO2, single nitrophenyl ethane, and both of them. Figure 4 includes Cu K-edge XANES spectra before and after reaction. Wavelet transform contour plots of the k2-weighted Cu K-edge EXAFS spectra for CuO-TiO2-C cocatalysts before and after reaction. Ti K-edge XANES spectra before and after reaction. Inset: Magnified image of the marked area in. Wavelet transform contour plots of the k2-weighted Ti K-edge EXAFS spectra for CuO-TiO2-C cocatalysts before and after reaction. The abovementioned reaction was implemented in a CO2-saturated 0.5 M PBS-0.01 M nitrophenyl ethane-3 vol% tetrahydrofuran electrolyte at -0.4 V *vs* RHE for 1 h. Figure 5 includes adsorption energy of nitrophenyl ethane on TiO2 (101) with lying and up-right position. The insets are their corresponding ball-and-stick models. Free energy profiles of L-Phe synthetic process. The Supplementary data is upload in Zenodo that can be opened with origin software. The following are the notes about the names involved in the SI table：aN: coordination number; bR: bond distance; cσ2: Debye-Waller factors; dΔ*E*0: the inner potential correction; R factor: goodness of fit.