CO 2 into valuable fuels and chemicals with renewable electricity, in which a persistent challenge is the control of product selectivity due to alternative multiple reaction pathways. Among the products of CO 2 ER, C 2+ products are more attractive owing to their high energy densities and economic values. In particular, ethanol as a liquid C 2 product with security in storage and transportation can function as a widely used solvent, a raw material in chemical synthesis, an additive to gasoline, a fuel source, etc. [1] However, it remains a challenge to design the electrocatalysts that enable CO 2 ER to ethanol with high selectivity due to the poor controllability of C-C coupling, which brings about competition with other C 1 or C 2+ products that have similar multiple intermediates on the catalyst surface. [2] In addition to the product selectivity, production efficiency in terms of current density is also highly important to CO 2 ER. To this end, flowcell is a device configuration that has been widely implemented for CO 2 ER in recent years; however, it calls for higher requirements for the electrocatalysts. The catalysts loaded onto the gas diffusion electrode (GDE) of flow-cell should possess both high electrical conductivity and gas permeability.To enable flow-cell CO 2 ER for ethanol production, it is imperative to design electrocatalysts with unique structures. The first goal for catalyst design is to maneuver the interaction between active sites and reaction intermediates for selective C−C coupling to ethanol. Cu-based materials possess a great capability of electrocatalyzing CO 2 to ethanol, [3] most of which benefit from the active sites of Cu δ+ (0 < δ < 1) species with moderate electron donor capability that bind with positively charged C atoms. Nevertheless, the selectivity and/or the current density for ethanol over these Cu-based electro catalysts are still low due to the fact that the Cu δ+ species are easily reduced to Cu 0 during CO 2 ER process. As a consequence, more than one liquid product other than ethanol are commonly obtained, which increases the downstream separation expense and limits the real application. To overcome this limitation, heteroatom doping, which can finely tailor the active sites of catalyst by hybridizing energy levels between the dopant and the pristine catalyst, [4] should be a powerful strategy for CO 2 electrocatalytic reduction (CO 2 ER) to multicarbon (C 2+ ) products is heavily pursued because of their commercial values, and the efficiency and selectivity have both attracted tremendous attention. A flow-cell is a device configuration that can greatly enhance the conversion efficiency but requires catalysts to possess high electrical conductivity and gas permeability; meanwhile, the catalysts should enable the reaction pathway to specific products. Herein, it is reported that V-doped Cu 2 Se nanotubes with a hierarchical structure can be perfectly compatible with flow-cells and fulfil such a task, achieving CO 2 electroreduction to ethanol with high efficiency and ...

It is a prospective tactic to actualize the carbon cycle via CO2 electroreduction reaction (CO2ER) into ethanol, where the crucial point is to design highly active and selective electrocatalysts. In this work, Br-doped CuO multilamellar mesoporous nanosheets with oxygen vacancies and cetyltrimethyl ammonium (CTA+) cations adsorption were synthesized on Cu foam by one-step liquid-phase method at room temperature. The nanosheets with numerous mesopores and rough edges provided abundant active sites for the adsorption of CO2 molecules and brought about a long retention time for intermediates. The dopant of Br– ions induced copious oxygen vacancies on CuO lattices, thereby reducing the activation energy of CO2 molecules and optimizing intermediate species and their adsorption behaviors, while adsorbed CTA+ cations modulated the O affinity of the Cu sites, favoring *OCH2CH3 intermediate converting to ethanol. The optimized Br1.95%-CuO can effectively catalyze CO2ER to C2H5OH in 0.1 M KHCO3. The faradaic efficiency of C2H5OH reached 53.3% with the partial current density of 7.1 mA cm–2 at a low potential of −0.6 V. In addition, after 14 h CO2ER test at −0.6 V, the current density and faradaic efficiency of C2H5OH on Br1.95%-CuO retained 99.6 and 93.9% of their original values, respectively, indicating its prominent catalytic stability. This work provided a novel strategy for designing a CuO catalyst by nonmetal doping and long-chain organic molecules adsorption with multiple active sites for optimizing intermediate species and their adsorption behaviors toward CO2ER to ethanol.

MnO 2 -60 NSs displayed partial current densities of 3.6 mA cm −2 at −0.7 V and 14.3 mA cm −2 at −1.0 V for CO. It also exhibited outstanding stability with negligibly decreased current densities after 12 h electrocatalysis at −0.5, −0.7, and −0.9 V. The synergy between Au NCs core and a-MnO 2 NSs shell is contributed to its prominent activity, selectivity, and stability for CO 2 ER to CO. This work integrates conductivity promotion and defect engineering by noble-metal@defective amorphous oxide core/shell nanostructure toward improved CO 2 ER.

Generating hydrogen via the alkali-water electrocatalytic hydrogen evolution reaction (HER) is a prospective avenue, in which the key point is to construct the electrocatalyst with excellent catalytic behavior. Herein, a Pt nanoparticles-loaded crystalline MoO 2 /amorphous Ni(OH) 2 hybrid nanosheets-composed nanofilm (PtNPs-c-MoO 2 /a-Ni(OH) 2 NF) on Ni foam was designed via a one-step solution-phase strategy for the alkaline HER. The hydrophilic amorphous Ni(OH) 2 in the hybrid nanosheets accelerated water dissociation, and the spillover effect of H atoms from Pt nanoparticles to MoO 2 in the hybrid nanosheets increased the utilization of the dissociated H atoms; moreover, the MoO 2 and the Ni(OH) 2 heterostructure in the hybrid nanosheets exposed copious active edge sites, which jointly enhanced the HER performance of the Pt NPs-c-MoO 2 /a-Ni(OH) 2 NF. The density functional theory (DFT) results showed that the water dissociation at Pt/Ni(OH) 2 (−0.24 eV) is thermodynamically more favored than that on Pt(111) (0.62 eV), and the recombination of one H* on Pt and one H* on MoO 2 could significantly reduce the energy barrier to only 0.05 eV. The optimized Pt 1.07% NPs-c-MoO 2 /a-Ni(OH) 2 NF with ∼2 nm ultrasmall Pt nanoparticles can achieve 10 mA cm −2 at an ultralow overpotential of 18 mV and 500 mA cm −2 at a low overpotential of 167 mV with superior long-term steadiness. Moreover, the mass activity of Pt 1.07% NPs-c-MoO 2 /a-Ni(OH) 2 NF achieved 8.24 mA μg Pt −1 at an overpotential of 70 mV, nearly 21.7-fold that of commercial Pt/C. Our synthesis strategy can be extended to obtain the Pd or Au nanoparticles-loaded c-MoO 2 /a-Ni(OH) 2 nanofilm with low noblemetal content for enhanced HER activities.

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