Electro‐oxidative organic upgrading, as an ideal alternative to sluggish oxygen evolution reaction (OER) performance, can effectively decrease energy consumption to boost hydrogen evolution reaction (HER) performance. However, developing highly active electrocatalysts for long‐term durable organic upgrading with high selectivity at large and steady current density remains challenging. Herein, hollow NiSe nanocrystals heterogenized with carbon nanotubes (h‐NiSe/CNTs) are fabricated via a facile one‐pot approach. The highly dispersed h‐NiSe/CNTs 3D network can efficiently facilitate rapid mass/electron diffusion, thus achieving highly active and long‐term stable electrocatalysis for catalyzing methanol to value‐added formate at high and steady current density (≈345 mA cm−2) with high Faradaic efficiency (>95%). This reaction replaces sluggish OER performance to reduce the energy consumption for boosting H2 generation by six times. The critical active species and methanol activation mechanism are systematically studied using X‐ray photoelectron spectroscopy, X‐ray absorption fine structure analysis, in situ Raman, and density functional theory calculations, indicating that the non‐ignorable SeOx collaborated with in situ formed NiOOH species can synergistically modulate the d band center to achieve an optimal adsorption for methanol selective oxidation and suppress the further oxidation to CO2, thus leading to active and stable electrolysis for producing value‐added formate with high selectivity and co‐generating H2 with less energy consumption.

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greenhouse gas effect and to simultaneously convert CO 2 to value-added industrial products. [1][2][3][4][5] However, the inertness of CO 2 molecule, the sluggish multi-electron transfer kinetics, and the competitive hydrogen evolution reaction (HER) during CO 2 RR result in the high overpotential (η) to various degrees, which jeopardizes CO 2 RR performance. [6,7] Therefore, it is highly desirable to develop the electrocatalysts that are capable of compromising the above impediments and simultaneously achieving the optimal CO 2 RR performance through specific optimization process.Formic acid (HCOOH) or formate, as an important liquid product from CO 2 RR, has been widely employed as chemical intermediates in various industrial processes. [8] The common industrial manufacture of HCOOH involves the carbonylation of methanol prior to the hydrolyzing of methyl formate. This process is performed in the liquid phase at elevated pressure, which is an energy-intensive and high-cost process. [9] In contrast, CO 2 RR to HCOOH requires a quite mild reduction condition. Currently, some metal-based materials (e.g., Sn, [10][11][12] Pb, [13][14][15] In, [16,17] and Cd [18,19] ) have been studied for HCOOH formation during CO 2 RR because of their suitable binding energy for the intermediate HCOO*. [20,21] However, the high cost and toxicity of these heavy metals (e.g., Pb, Cd, In, etc.) preclude their scalability. Remarkably, Bi-based materials have attracted much attention owing to their low toxicity, earth-abundance, and good selectivity toward formate formation. Various features of Bi-based materials, such as size, morphology, and electrocatalysts with conductive support, have been widely investigated to achieve enhanced electrocatalytic activity and selectivity. [22][23][24] Nevertheless, their low current density (j) and high overpotential are still the bottlenecks that restrict their practical applications at industrial level. [25,26] Therefore, it is of great importance to fabricate the highly effective and stable Bi-based electrocatalysts, to explore the associated reaction mechanism in order to achieve an improved selectivity toward formate.The complicated multi-electron transfer steps during CO 2 RR suggest the importance of charge transfer ability of electrocatalyst. [27,28] Various studies on Bi-based electrocatalysts, including the construction of Bi 2 O 3 nanosheets (NSs) on multi-channel carbon matrix support, [29] the fabrication of Bi 2 O 3 @C derived Electrochemical CO 2 reduction reaction (CO 2 RR) is a promising approach to convert CO 2 to carbon-neutral fuels using external electric powers. Here, the Bi 2 S 3 -Bi 2 O 3 nanosheets possessing substantial interface being exposed between the connection of Bi 2 S 3 and Bi 2 O 3 are prepared and subsequently demonstrate to improve CO 2 RR performance. The electrocatalyst shows formate Faradaic efficiency (FE) of over 90% in a wide potential window. A high partial current density of about 200 mA cm −2 at −1.1 V and an ultralow onset potential with formate FE of ...

The ever-increasing concern for adverse climate changes has propelled worldwide research on the reduction of CO2 emission. In this regard, CO2 electroreduction (CER) to formate is one of the promising approaches to converting CO2 to a useful product. However, to achieve a high production rate of formate, the existing catalysts for CER fall short of expectation in maintaining the high formate selectivity and activity over a wide potential window. Through this study, we report that Bi2O3 nanosheets (NSs) grown on carbon nanofiber (CNF) with inherent hydrophobicity achieve a peak formate current density of 102.1 mA cm–2 and high formate Faradaic efficiency of >93% over a very wide potential window of 1000 mV. To the best of our knowledge, this outperforms all the relevant achievements reported so far. In addition, the Bi2O3 NSs on CNF demonstrate a good antiflooding capability when operating in a flow cell system and can deliver a current density of 300 mA cm–2. Molecular dynamics simulations indicate that the hydrophobic carbon surface can repel water molecules to form a robust solid–liquid–gas triple-phase boundary and a concentrated CO2 layer; both can boost CER activity with the local high concentration of CO2 and through inhibiting the hydrogen evolution reaction (HER) by reducing proton contacts. This water-repelling effect also increases the local pH at the catalyst surface, thus inhibiting HER further. More significantly, the concept and methodology of this hydrophobic engineering could be broadly applicable to other formate-producing materials from CER.

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