Facet-dependent electrooxidation of propylene into propylene oxide over Ag3PO4 crystals

Abstract

The electrooxidation of propylene into propylene oxide under ambient conditions represents an attractive approach toward propylene oxide. However, this process suffers from a low yield rate over reported electrocatalysts. In this work, we develop an efficient electrocatalyst of Ag3PO4 for the electrooxidation of propylene into propylene oxide. The Ag3PO4 cubes with (100) facets exhibit the highest yield rate of 5.3 gPO m−2 h−1 at 2.4 V versus reversible hydrogen electrode, which is 1.6 and 2.5 times higher than those over Ag3PO4 rhombic dodecahedra with (110) facets and tetrahedra with (111) facets, respectively. The theoretical calculations reveal that the largest polarization of propylene on Ag3PO4 (100) facets is beneficial to break the symmetric π bonding and facilitate the formation of C-O bond. Meanwhile, Ag3PO4(100) facets exhibit the lowest adsorption energies of *C3H6 and *OH, inducing the lowest energy barrier of the rate-determining step and thus accounting for the highest catalytic performance.

Crystal Engineering Enables Cobalt-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for H2O2 Production

“…The faraday efficiency (FE) of ZnCo-ZIF-C3 (>85% at relatively low current density) is also the highest among all samples (Figure e), indicating remarkable H 2 O 2 selectivity. The decrease of FE at higher current density may be attributed to the competing H 2 O 2 reduction reaction (H 2 O 2 RR) process . The cumulative H 2 O 2 yield of ZnCo-ZIF-C3 increases linearly within 2 h continuous test, indicating constant production of H 2 O 2 (Figure f).…”

Dynamically Reversible Interconversion of Molecular Catalysts for Efficient Electrooxidation of Propylene into Propylene Glycol

“…Compared with the AgPz, the hydrogen bond between the pyrrolic N–H and OH for AgPz-H vac was broken, resulting in the weaker E B (*OH) of −2.75 eV. It has been reported that strong E B (*OH) favored the dissociation of H 2 O into *OH, whereas the weak E B (*OH) was beneficial to the coupling of *OH and propylene. − In this way, the dynamically reversible interconversion between AgPz and AgPz-H vac was considered to facilitate the dissociation of H 2 O into *OH and the transfer of *OH to propylene simultaneously. We conducted the ab initio molecular dynamics calculations for each elementary step involved in the electrooxidation of propylene into PG over AgPz and AgPz-CH 3 with the solvent effect (Figure S18).…”

“…18,19 The strong E B (*OH) favors the dissociation of H 2 O into *OH, whereas the transfer of *OH to propylene would be impeded. 19,20 On the contrary, the weak E B (*OH) is beneficial to the combination of *OH and propylene but detrimental for *OH generation. 21,22 As such, the catalytic performance for propylene electrooxidation would be restricted due to the scaling relationship of the E B (*OH) over the conventional catalysts.…”

“…As shown in Figure 4a, the peaks at 1560 and 1367 cm −1 were assigned to the vibrations of the −C�C− in *Pr and −CH 2 − in *PrOH. 19,36 When the applied potentials were increased from 1.6 to 2.4 V vs Ag/AgCl, the intensity of *PrOH was increased, whereas the intensity of *Pr was gradually decreased, indicating the transformation of *Pr into *PrOH. Apart from the characteristic peaks for *Pr and *PrOH, the peak located at 1246 cm −1 was assigned to the C− N stretching in AgPz-H vac , 37−40 which was in accord with the calculated peak position (Figure S21).…”

Reaction Mechanism and Selectivity Tuning of Propene Oxidation at the Electrochemical Interface

“…Propene is an important feedstock (over 130 million tons of capacity) for manufacturing numerous commodity chemicals in the industry. − Traditionally, propene conversion is via thermocatalysis. With the dramatic increase in available renewable electricity in recent years, directly converting propene via electrochemical approaches under moderate conditions becomes a capable alternative. − As an anodic reaction, propene oxidation may replace the oxygen evolution reaction in electrolyzers to couple with cathodic hydrogen evolution or the CO 2 reduction reaction. The lower working potential of propene oxidation than the OER and high value-added products rather than O 2 can greatly benefit the energy efficiency and economic effectiveness of the electrolyzers .…”