Highly Selective Hydrogenation of CO₂ to Ethanol via Designed Bifunctional Ir₁–In₂O₃ Single-Atom Catalyst

Abstract

Recently, CO 2 hydrogenation for the controlled growth of the carbon chain to produce high-value C 2 or C 2+ products has attracted great interest, where achieving high selectivity for a specific product remains a challenge, especially for ethanol. Herein, we have designed a bifunctional Ir 1 −In 2 O 3 single-atom catalyst, integrating two active catalytic centers by anchoring the monatomic Ir onto the In 2 O 3 carrier. This Ir 1 −In 2 O 3 single-atom catalyst is efficient for the hydrogenation of CO 2 in liquid, yielding a high selectivity for ethanol (>99%) with an excellent initial turnover frequency (481 h −1 ). Characterization shows that the isolated Ir atom couples with the adjacent oxygen vacancy forming a Lewis acid−base pair, which activates the CO 2 and forms the intermediate species of carbonyl (CO*) adsorbed on the Ir atom. Coupling this CO* with the methoxide adsorbed on the In 2 O 3 forms a C−C bond. The strategy of this effective bifunctional single-atom catalyst by synergistically utilizing the distinct catalytic roles of the single-atom site and the substrates provides a new avenue in catalyst design for complex catalysis.

The Strategy for Constructing the Structure: Pt-O-Ce3+ Applied in Efficient NOx Removal

“…Uniformly, the preparation method of PtCe(C) catalysts was the same as that of PtCe(N) catalysts, except for replacing the platinum nitrate with chloroplatinic acid (H 2 PtCl 6 ). By means of heat treatment and calcination, [PtCl 6 ] 2− species were dechlorinated and little Cl ion was detected (Zhang et al, 2019;Ye et al, 2020). Meanwhile, the Pt content was the same on the PtCe(N) and PtCe(C) catalyst (0.204% vs. 0.209%), as determined by ICP-MS. Noteworthily, the Pt atoms from platinum nitrate solution and chloroplatinic acid solution were divalent [Pt(II)] and tetravalent [Pt(IV)], respectively.…”

Highly Selective Synthesis of Ethanol via CO2 Hydrogenation over CoMoCx Catalysts

“…Based on the experimental results and literatures, [46,2,11,17,14] the pathways of CO 2 hydrogenation to EtOH over MoCoC x -800 was proposed. Firstly, the reaction is initiated by activating H 2 on MoCoC x -800, followed by CO 2 hydrogenation with dissociated H* to HCOO* species, and then continue hydrogenation to form CH 3 O*.…”

“…Due to the excellent ability to activate CO 2 /H 2 and catalyze CÀ C coupling, previous researches on the CO 2 hydrogenation to ethanol mainly is focused on noble-metal catalysts. [11][12][13][14] Under the conditions of 200°C and total pressure of 6 MPa, Au/TiO 2 gave a high ethanol yield of 869.3 mmolg Au À 1 h À 1 with a high stability. [15] Pd/Fe 3 O 4 single-atom catalyst was also showed the high space-time yield (413 mmolg Pd À 1 h À 1 ) of ethanol at 300°C and 1 bar.…”

Erbium Single Atom Composite Photocatalysts for Reduction of CO2 under Visible Light: CO2 Molecular Activation and 4f Levels as an Electron Transport Bridge

“…With the advent of the era of single-atom catalysis, rare-earth single-atom catalysts are gradually emerging in the field of photocatalysis. [49] Reducing rare-earth nanomaterials to a single-atom scale, the unique structural characteristics of the rare-earth single atom might give them different or unexpected properties from the nanoscale homologs, which provides a new opportunity for efficient photocatalytic CO 2 reduction. [50,51] Here, erbium (Er) single atom composite photocatalysts were successfully constructed by in situ synthesis and chemisorption, respectively.…”