Active and conductive layer stacked superlattices for highly selective CO2 electroreduction

Abstract

Metal oxides are archetypal CO2 reduction reaction electrocatalysts, yet inevitable self-reduction will enhance competitive hydrogen evolution and lower the CO2 electroreduction selectivity. Herein, we propose a tangible superlattice model of alternating metal oxides and selenide sublayers in which electrons are rapidly exported through the conductive metal selenide layer to protect the active oxide layer from self-reduction. Taking BiCuSeO superlattices as a proof-of-concept, a comprehensive characterization reveals that the active [Bi2O2]2+ sublayers retain oxidation states rather than their self-reduced Bi metal during CO2 electroreduction because of the rapid electron transfer through the conductive [Cu2Se2]2- sublayer. Theoretical calculations uncover the high activity over [Bi2O2]2+ sublayers due to the overlaps between the Bi p orbitals and O p orbitals in the OCHO* intermediate, thus achieving over 90% formate selectivity in a wide potential range from −0.4 to −1.1 V. This work broadens the studying and improving of the CO2 electroreduction properties of metal oxide systems.

Highly Strained Bi‐MOF on Bismuth Oxyhalide Support with Tailored Intermediate Adsorption/Desorption Capability for Robust CO2 Photoreduction

“…After interacted with CO 2 , the 1π and 7σ frontier molecule orbitals of CO 2 2p for both the strain‐free and strained models shifts downwards the Fermi level, indicating the fast adsorption of CO 2 . Notably, for the strained one, new non‐degenerate orbital overlapping near 1π and intensified overlapping of 7σ orbitals apparently appear, demonstrating the favourable activation of absorbed CO 2 molecules [63] . Besides, the integrated COHP (iCOHP) value for the strained model is calculated to be −0.136, lower than that of the unstrained model, indicating the weakened bonding strength over strain engineering.…”

“…Notably, for the strained one, new non-degenerate orbital overlapping near 1π and intensified overlapping of 7σ orbitals apparently appear, demonstrating the favourable activation of absorbed CO 2 molecules. [63] Besides, the integrated COHP (iCOHP) value for the strained model is calculated to be À 0.136, lower than that of the unstrained model, indicating the weakened bonding strength over strain engineering. And meanwhile, the bond length has also correspondingly changed from 3.10 Å to 3.12 Å, further demonstrating the weakened mutual interactions between CO 2 and strained Bi-MOF.…”

The Critical Role of Initial/Operando Oxygen Loading in General Bismuth-Based Catalysts for Electroreduction of Carbon Dioxide

“…In summary, the multiple characterizations indicate that the metalloid intermediate states probably exist in all Bi-based catalysts, while the in situ oxygen level in such intermediate, which also demonstrates a strong correlation to the initial lattice oxygen and/or valence state of Bi, presumably plays a crucial role in the overall CO 2 RR performance. Based on this hypothesis, we further surveyed a number of Bi-based catalysts as reported in recent literatures. ,,− As summarized in Figure , an obvious correlation is indeed observed between the Bi valence state in the as-prepared catalytic materials and the reported FE HCOOH in carbon dioxide reduction. Interestingly, the 2D metallic bismuthene also shows the highest-level performance, which could be rationalized by the strong surface adsorption of anion and oxygens (presumably from the inevitable oxidation of 2D structure with high surface energy), leading to an actual high oxidation level on the bismuth surface.…”

Two-dimensional materials: synthesis and applications in the electro-reduction of carbon dioxide

“…2D: 2-dimensional; FE: Faradaic efficiency; EDS: energy dispersive spectroscopy. solution [141] . The as-prepared catalyst exhibits an FE CH3OH of 67.4% with a current density of approximately 122.7 mA cm -2 in a typical H-cell at -1.2 V vs. RHE using an ionic liquid (IL)-based electrolyte.…”