README: Direct propylene epoxidation via water activation over Pd-Pt electrocatalysts

https://doi.org/10.5061/dryad.s7h44j1dd

Tabulated data underlying figures in the manuscript and the supplementary materials.
The Excel file includes multiple sheets named by the figure numbers.

The details of each tab are as follows:

Fig.1DE

Direct electrochemical propylene-epoxidation performance with different compositions of Pd-Pt-on-carbon catalysts in (D) water-acetonitrile electrolyte and (E) aqueous electrolyte.

Data labeling:

FE_PO; Faradaic efficiency toward propylene oxide

FE_PG; Faradaic efficiency toward propylene glycol

Fig. 2A S6 - xrd

Intensities of the X-ray diffraction signal at various diffraction (Intensity (a.u.) vs. two theta (degrees)).

Fig 2B,3B,S10 XAS Pd K edge

EXAFS and XANES spectra of standards and catalysts at Pd K-edge.

Fig 2C,3A,S11 XAS Pt L3 edge

EXAFS and XANES spectra of standards and catalysts at Pt L3-edge.

Data labeling:

numbers such as '045','085', '105', '115' mean 0.45, 0.85, 1.05, 1.15, respectively.

'neg 135' ; a condition when -1.35 V vs. Fc/Fc+ was applied

'afterneg 105' ; a condition when 1.05 V vs. Fc/Fc+ was applied after a negative potential (-1.35 V vs. Fc/Fc+) was applied

Fig.2D Fig S7

Cyclic voltammetry traces of the catalysts. The scans were recorded at 50 mV/sec scan rate with 85% automatic iR-compensation (i=current; R=resistance).

Fig. 2E - XPS Pd

High-resolution Pd 3d XPS spectra of annealed Pd/C and PdPt/C catalysts.

Fig. 2F - XPS Pt

High-resolution Pt 4f XPS spectra of annealed Pt/C and PdPt/C catalysts.

Fig. 4

Kinetic data on direct anodic epoxidation with PdPtOx/C catalysts. (A) Anodic potential dependence of current density at 1 atm propylene in a 10 M water, 0.4 M tetrabutylammonium tetrafluoroborate (TBABF4) acetonitrile solution. (B) Water molar concentration dependences of propylene-epoxidation current density at different propylene partial pressures. (C) Propylene partial-pressure dependences of propylene-epoxidation current density at different water concentrations. (E) Simulated propylene partial-pressure dependences of intermediate species coverage at 10 M water, 1.1 V versus Fc/Fc+ condition. Potentials were 100% iR-compensated.

Fig. 5

Correlation between the alkene electrophilicity index and the direct anodic epoxidation rate.

Fig. S4

Cell performances with (B, C) water-acetonitrile blended electrolyte and (D) aqueous electrolyte.

Data labeling:

'E_w (V)' ; Measured working electrode (anode) potential (vs. Fc/Fc+)

'Ew vs FC-IR' , 'E_w-ircomp' ; Measured working electrode (anode) potential (vs. Fc/Fc+) minus the resistive voltage (i.e. IR) between anode and reference electrodes (i.e. iR-compensated anode potential).

'cellV-ir', 'cell voltage-ircomp' ; Cell voltage minus the resistive voltage of the entire cell (i.e. iR-compensated cell voltage)

Fig. S5

DLC measurement and ECSA-normalized propylene epoxidation performance with different compositions of Pd-Pt-on-carbon catalysts.

Acronyms:

DLC; double-layer capacitance

ECSA; electrochemically active surface area

Fig. S8

Comparison of annealed PdPt/C catalyst performances at a constant potential of 1.1 V vs. Fc/Fc+ (100% iR-compensated).

Fig. S9

Direct anodic propylene epoxidation performance with different compositions of Pd-Pt alloy catalysts annealed at 400 ℃.

Fig. S12

Water dependences of propylene epoxidation current density.

Data labeling:

x_h2o; water mole ratio

a_x_water; water activity

i_epox; epoxidation current density

Fig. S13

Propylene dependences of propylene epoxidation current density.

Data labeling:

a_propylene; propylene activity, estimated as the mole ratio of propylene in the gas feed

a_water; water activity

Fig. S14

Product distributions with different catalysts annealed at 400 ℃, constant current at 40 mA/cm2. 10 sccm of propylene was introduced to the electrolyte containing 0.4 M TBABF4 and 10 M water in acetonitrile.

Fig. S15

Deuterium kinetic isotope effects on epoxidation rate catalyzed by PdPtOx/C.

Data labeling:

k_H / k_sample; deuterium kinetic isotope effect , which is estimated by the ratio of the epoxidation rates in protonated and deuterated systems.

Fig. S17

Water activity measurements using headspace-gas chromatography-TCD.

Fig. S18

Conversion of propylene oxide (PO) to propylene glycol (PG) in aqueous electrolytes with varying pHs. PO consumption and PG formation were monitored and quantified by 1H-NMR.

Fig. S19

High-resolution Pt 4f XPS spectra of PdPtOx/C sample before and after electrolysis.

Fig. S20

Effects of epoxide and oxygen concentrations on propylene epoxidation rate.

Fig. S21

Epoxidation Faradaic efficiencies and rates at different potentials (100% iR-compensated).

kinetic data compilation

Epoxidation current densities and Faradaic efficientes at different potentials, water concentrations, and propylene pressures.