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The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to convert CO2 to carbon‐based fuels and to simultaneously reduce the emission of greenhouse gases into the atmosphere. In this work, the bismuth subcarbonate nanoflowers (BOC NFs) are facilely prepared through a one‐pot synthesis method for efficient formate electrosynthesis through CO2RR. Benefiting from the crystal structure and sheet‐stacked morphology, the in situ measurements and theoretical calculation results reveal the self‐reinforced CO2 adsorption properties and rapid CO2 adsorption–desorption kinetics on the catalyst surface, which significantly facilitate the CO2RR process. As a result, the desirable Faradaic efficiencies of over 90%, with a maximum value of 98.9%, toward formate formation, are achieved in a wide potential window from −0.8 to −1.4 V in an H‐type cell. Moreover, in a flow cell, the superior intrinsic activity of BOC NFs guarantees the high throughput electrocatalytic performance of CO2RR and the FEformate of over 90% with high current density is achieved in a potential range as wide as 1200 mV, demonstrating the great potential of BOC NFs for practical CO2RR applications. These results underscore the effectiveness of designing electrocatalysts with self‐reinforced CO2 adsorption properties to improve electrocatalytic performance for efficient CO2RR. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The development of new promising metal-free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three-dimensional (3D) architecture of 1D graphitic carbon nitride (g-C3N4) nanoribbons with 2D graphene sheets has been developed by a one-step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g-C3N4 nanoribbon-graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade−1, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm−2, superior to those non-metal materials and well-developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal-free catalyst for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Surface re-construction was a common phenomenon for non-oxide compound electrocatalysts in anodic oxidation reaction in alkaline electrolyte but surface deactivation arising from excessive oxidation/hydroxylation was critical hindrance to the long-term stability. Herein, a unique anode-cathode interchangeable electrocatalysis strategy is proposed for methanol upgrading reaction (MUR) and hydrogen co-generation in membrane-free electrolyzer. A periodical electrolysis is taken place for the Ni 3 S 2 /CNTs electrode at positive/negative currents over time. Compared with the traditional chronopotentiometry mode, the MUR-HER coupled reactions by periodically switching anode/cathode per hour present an excellent long-term stability at high current densities of ± 100 mA cm−2, in which the Faradaic efficiencies for both H 2 and value-added formate are greater than 95%. Substantial experimental results and deep theoretical DFT studies signify that the successful application of this strategy is mainly due to the reversible modulation of oxidation/hydroxylation status on Ni 3 S 2 surface, which effectively prevent the surface active structures of electrocatalysts from over-oxidation. [Display omitted] • A periodical electrolysis is taken place with Ni 3 S 2 /CNTs electrode at positive or negative current over time. • Long-term stable methanol upgrading and hydrogen co-generation are achieved in a membrane-free electrolyzer. • Substantial XPS, XAFS and DFT studies indicate that the surface critical active sites can be in situ revived. • Such unique anode-cathode interchangeable strategy effectively prevents catalyst surface from over-oxidation. • It successfully brings about the reversible modulation of oxidation/hydroxylation status on Ni 3 S 2 surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • OH− ions were created by the in-situ synthesis of CdCO 3 (i-CdCO 3) on the electrode. • The i-CdCO 3 delivers near-unity selectivity for the electroreduction of CO 2 to CO. • An ultrahigh mass activity of 165.1 mA mg−1 was achieved on i-CdCO 3 at − 1.26 V. • The superior CO selectivity is due to an increased local pH which inhibits HER. Electrochemical reduction of CO 2 to CO is an attractive approach for the sustainable carbon cycle. However, the activity and selectivity of the CO 2 reduction reaction (CO 2 RR) are often limited by the competitive hydrogen evolution reaction (HER) in aqueous media. In this work, in-situ generated hydroxides were introduced by the synthesis of rhombohedral CdCO 3 crystals (i-CdCO 3) under electrochemical CO 2 RR conditions. The generated hydroxides contribute to an increased local pH at the electrode/electrolyte interface, thereby effectively inhibiting HER. As a result, the obtained i-CdCO 3 exhibits remarkably higher CO Faradaic efficiency (over 90%) in a broad potential range, where a near 100% selectivity is achieved, as compared to a pre-synthesized CdCO 3 with similar morphology. Moreover, i-CdCO 3 delivers a large current density of − 24.8 mA mg−1 at − 1.26 V, together with a good stability of 36 h with negligible degradation, further demonstrating its superiority for efficient CO 2 RR. This study proposes a promising design strategy to boost the selectivity of CO 2 RR systems through in-situ producing hydroxides near the electrode to suppress the unfavorable HER. [ABSTRACT FROM AUTHOR]