Porosity engineering of biochar‐based single‐atom Ni catalysts to promote CO₂ electroreduction over a broad potential window

Abstract

Developing electrocatalysts for CO2 electroreduction with high activity and superior selectivity is extremely important and desirable from both academic and industrial perspectives. However, owing to competition with hydrogen evolution, highly efficient CO2 reduction is mostly achieved with high CO selectivity in a narrow potential range, which is incompatible with a large cell voltage required for industrial‐level CO2 reduction. Herein, we report an effective strategy to regulate CO2 reduction performances of single‐atom Ni electrocatalysts over a broad potential window by engineering their pore structures (micropores, mesopores, or hierarchical pores with both micropores and mesopores). It is revealed that hierarchically pores can significantly promote CO2 reduction efficiency of single‐atom Ni electrocatalysts. The hierarchically porous electrocatalyst achieves a maximum CO Faradaic efficiency (FECO) of 97.4% at −1.2 V (vs. RHE) and shows high FECO of >85% over a broad potential window from −0.7 to −1.7 V, much superior to electrocatalysts with other pore structures. More impressively, turnover frequency of the hierarchically porous electrocatalyst increases rapidly with increasing the applied potential and reaches 50,067 h−1 at −1.7 V. Such CO2 electroreduction promotion could be attributed to a synergistic effect of micropores for enhancing CO2 adsorption and mesopores for facilitating rapid release of product bubbles, which significantly improves CO2 reduction and suppresses hydrogen evolution.

Breaking the scaling relationship via lattice expansion of Ag for CO2 electroreduction over a wide potential window

“…Moreover, the large current density is normally achievable at high overpotential, but the FE CO dramatically declines when operating at more negative potentials than the optimum selectivity potential. 41,42 To address this problem, researchers have made some progress by tailoring Ag electrocatalysts. 36,[43][44][45] However, the potential window of 400-600 mV for effective CO 2 RR is still far from meeting the requirements of practical utilization.…”

“…This makes them unappealing in practical applications because of voltage fluctuation in unstable renewable energy sources. Moreover, the large current density is normally achievable at high overpotential, but the FE CO dramatically declines when operating at more negative potentials than the optimum selectivity potential 41,42 . To address this problem, researchers have made some progress by tailoring Ag electrocatalysts 36,43–45 .…”

Synthesis of Few-Layer Bismuthene for Efficient Electroreduction of CO2 to Formate

“…2 In pursuit of this challenging goal, developing efficient electrocatalysts with considerable activity and stability is a prerequisite. 3 Recently, Bi-based materials have been widely explored for the selective formation of formate during electrochemical CO 2 RR. 4 The emergence of Bi-based electrocatalysts with divergent morphologies, e.g., Bi nanoparticles, 5 nanowires, 6 nanotubes, 7 nanodendrites, 8 and nanosheets, 9 exhibited significant improvements in catalytic activity and FE formate .…”

“…To mitigate the surge of CO 2 concentration in the atmosphere, electrochemical CO 2 reduction reaction (CO 2 RR) to formate is an auspicious strategy to neutralize carbon emissions and has attracted enormous attention in the field . In pursuit of this challenging goal, developing efficient electrocatalysts with considerable activity and stability is a prerequisite . Recently, Bi-based materials have been widely explored for the selective formation of formate during electrochemical CO 2 RR .…”

Boosting CO2 electroreduction to HCOOH at high current density through tuning the electronic metal‐support interaction

“…Electrocatalytic CO 2 reduction to high value‐added chemicals is currently potential strategy to alleviate energy consumption and environmental pollution caused by fossil fuel combustion 1–11 . Among the numerous reduction products, formic acid (HCOOH) has attached extensive focus ascribed to its high energy density and widely industrial application prospects 12–17 .…”