High‐Dispersive Pd Nanoparticles on Hierarchical N‐Doped Carbon Nanocages to Boost Electrochemical CO₂ Reduction to Formate at Low Potential

Abstract

Electrochemical CO2 reduction reaction (CO2RR) to value‐added chemicals/fuels is an effective strategy to achieve the carbon neutral. Palladium is the only metal to selectively produce formate via CO2RR at near‐zero potentials. To reduce cost and improve activity, the high‐dispersive Pd nanoparticles on hierarchical N‐doped carbon nanocages (Pd/hNCNCs) are constructed by regulating pH in microwave‐assisted ethylene glycol reduction. The optimal catalyst exhibits high formate Faradaic efficiency of >95% within −0.05–0.30 V and delivers an ultrahigh formate partial current density of 10.3 mA cm−2 at the low potential of −0.25 V. The high performance of Pd/hNCNCs is attributed to the small size of uniform Pd nanoparticles, the optimized intermediates adsorption/desorption on modified Pd by N‐doped support, and the promoted mass/charge transfer kinetics arising from the hierarchical structure of hNCNCs. This study sheds light on the rational design of high‐efficient electrocatalysts for advanced energy conversion.

Bending two-dimensional Cu(i)-based coordination networks to inverse electrocatalytic HER/CO2RR selectivity

“…S48 and S49†). 60,61 Therefore, the differences in Δ G max values should mainly arise from the product structures ( i.e. , CO*–*CHO and H*–*OH).…”

Highly Dispersed Quasi-1 nm Ruthenium Nanoclusters on Hierarchical Nitrogen-Doped Carbon Nanocages Constructed by Surface-Constrained Sintering for Alkaline Hydrogen Evolution

“…40−44 Moreover, the abundant micropores and N-dopants on the surface can easily capture metal species and regulate the metal−support interaction, showing great promise to construct highly active and stable catalysts. 45,46 Herein, by taking the hierarchical N-doped carbon nanocages (hNCNC) as support, highly dispersed Ru nanoclusters are constructed by a simple adsorption-annealing process governed by surface-constrained sintering, which present a quasi-1 nm size and strong metal− support interaction due to the anchoring effect of N dopants. The optimized electrocatalyst exhibits the ultralow overpotential of 21 mV at 10 mA cm −2 and excellent stability in 1 M KOH, superior to the Pt/C benchmark.…”

“…To regulate the electronic structure of Ru-based catalysts and thus optimize the *H adsorption/desorption energy, many strategies have been developed, such as morphology/size control, alloying with other metals, heteroatoms-doping, and support engineering. − Downsizing the Ru species from nanoparticles (>2 nm) to nanoclusters (0.2–2 nm) and even single-sites (<0.2 nm) can not only greatly change the electronic structure but also substantially increase the atom utilization. , Among them, the Ru–N x single-sites are favorable for the *H adsorption/desorption but unfavorable for the H 2 O dissociation due to the absence of adjacent sites, usually resulting in the inferior HER performances in alkaline/neutral electrolytes. , In contrast, the Ru nanoclusters can achieve the “win-win” goal of electronic structure regulation and high active sites for H 2 O dissociation, suggesting the great potential in the alkaline HER. , The small-sized Ru nanoclusters usually mean easy agglomeration due to their high surface energy; hence, support engineering is necessary to immobilize Ru nanoclusters by improving the metal–support interaction. ,− The 3D N-doped carbon supports have shown great promise in the construction of noble metal catalysts since their 3D hierarchical porous structure and high conductivity can facilitate the charge/mass synergic transport and the high utilization of metal active species. , In recent years, our group has developed a unique support of hierarchical carbon-based nanocages with combined merits of large specific surface area (SSA), high conductivity, coexisting micromeso-macropores, and easy heteroatoms doping, becoming a multifunctional platform for energy storage and conversion. − Moreover, the abundant micropores and N-dopants on the surface can easily capture metal species and regulate the metal–support interaction, showing great promise to construct highly active and stable catalysts. , Herein, by taking the hierarchical N-doped carbon nanocages (hNCNC) as support, highly dispersed Ru nanoclusters are constructed by a simple adsorption-annealing process governed by surface-constrained sintering, which present a quasi-1 nm size and strong metal–support interaction due to the anchoring effect of N dopants. The optimized electrocatalyst exhibits the ultralow overpotential of 21 mV at 10 mA cm –2 and excellent stability in 1 M KOH, superior to the Pt/C benchmark.…”

Amphipathic Surfactant on Reconstructed Bismuth Enables Industrial-Level Electroreduction of CO2 to Formate

“…5,6 Among the various products derived from the CO 2 RR, formic acid/formate has gained considerable attention due to its potential as a hydrogen carrier for fuel cells as well as a fundamental raw material for chemical feedstock. 7,8 Technoeconomic analysis has indicated several benefits of formic acid/formate, including high single-product selectivity and substantial economic advantages, which highlight its suitability for the industrial-scale production via the CO 2 RR. 9,10 To realize this potential, the development of an effective electrocatalyst with outstanding selectivity and activity is essential.…”

“…The relentless growth of the global economy has led to an overreliance on fossil fuels, resulting in a significant increase in the atmospheric CO 2 level and posing a critical threat to the environment. , To achieve sustainable development, it is imperative to devise efficient strategies that promote carbon neutrality. , One promising solution is the electrochemical CO 2 reduction reaction (CO 2 RR), powered by renewable resources, which not only facilitates carbon neutrality but also enables the production of value-added chemicals. , Among the various products derived from the CO 2 RR, formic acid/formate has gained considerable attention due to its potential as a hydrogen carrier for fuel cells as well as a fundamental raw material for chemical feedstock. , Technoeconomic analysis has indicated several benefits of formic acid/formate, including high single-product selectivity and substantial economic advantages, which highlight its suitability for the industrial-scale production via the CO 2 RR. , To realize this potential, the development of an effective electrocatalyst with outstanding selectivity and activity is essential. Among the p -block metals, such as Sn, In, and Bi, that possess oxygenophilic properties, Bi stands out as a promising candidate due to its low toxicity and cost effectiveness. , However, conventional Bi-based catalysts face limitations of a narrow potential window for high Faradaic efficiency (FE formate ) and high overpotential (<−0.8 V vs. reversible hydrogen electrode (RHE)) for formate production, making them incompatible with fluctuating renewable power sources and resulting in high energy consumption. , Moreover, the insufficient current density ( J formate ) of <100 mA·cm –2 hinders large-scale formate production. , Thus, developing Bi-based electrocatalysts with low overpotential, high FE formate at a wide potential window, and a large J formate exceeding 100 mA·cm –2 is essential for their industrial-level CO 2 RR application to produce formate.…”