DOI: 10.5061/dryad.s7h44j1dd
title: Data from: Direct propylene epoxidation via water activation over Pd-Pt electrocatalysts

description: Direct electrochemical propylene epoxidation using water oxidation
 intermediates presents a sustainable alternative to existing routes that
 involve hazardous chlorine or peroxide reagents. Here we report an
 oxidized palladium-platinum alloy catalyst (PdPtOx/C), which reaches a
 Faradaic efficiency of 66±5% toward propylene epoxidation at 50 mA/cm2 at
 ambient temperature and pressure. Embedding platinum into the palladium
 oxide crystal structure stabilized oxidized platinum species, resulting in
 improved catalyst performance. The reaction kinetics suggest that
 epoxidation on PdPtOx/C proceeds through electrophilic attack by
 metal-bound peroxo (OO*) intermediates. This work demonstrates an
 effective strategy for selective electrochemical oxygen-atom transfer from
 water, without mediators, for diverse oxygenation reactions.
description: # Direct propylene epoxidation via water activation over Pd-Pt
 electrocatalysts 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. &gt; Data labeling: &gt; &gt; FE_PO; Faradaic
 efficiency toward propylene oxide &gt; &gt; 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. &gt;
 Data labeling: &gt; &gt; numbers such as '045','085',
 '105', '115' mean 0.45, 0.85, 1.05, 1.15,
 respectively. &gt; &gt; 'neg 135' ; a condition when -1.35 V vs.
 Fc/Fc+ was applied &gt; &gt; '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. &gt;
 Data labeling: &gt; &gt; 'E_w (V)' ; Measured working electrode
 (anode) potential (vs. Fc/Fc+) &gt; &gt; '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). &gt; &gt;
 '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. &gt; Acronyms: &gt; &gt; DLC; double-layer capacitance &gt;
 &gt; 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. &gt; Data labeling: &gt; &gt; x_h2o; water
 mole ratio &gt; &gt; a_x_water; water activity &gt; &gt; i_epox;
 epoxidation current density **Fig. S13** Propylene dependences of
 propylene epoxidation current density. &gt; Data labeling: &gt; &gt;
 a_propylene; propylene activity, estimated as the mole ratio of propylene
 in the gas feed &gt; &gt; 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. &gt; Data labeling: &gt; &gt; 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.