High-performance CO2 Reduction Research Articles

Backbone Engineering of Polymeric Catalysts for High-Performance CO2 Reduction in Bipolar Membrane Zero-Gap Electrolyzer.

Bipolar membranes (BPMs) have emerged as a promising solution for mitigating CO2 losses, salt precipitation and high maintenance costs associated with the commonly used anion-exchange membrane electrode assembly for CO2 reduction reaction (CO2RR). However, the industrial implementation of BPM-based zero-gap electrolyzer is hampered by the poor CO2RR performance, largely attributed to the local acidic environment. Here, we report a backbone engineering strategy to improve the CO2RR performance of molecular catalysts in BPM-based zero-gap electrolyzers by covalently grafting cobalt tetraaminophthalocyanine onto a positively charged polyfluorene backbone (PF-CoTAPc). PF-CoTAPc shows a high acid tolerance in BPM electrode assembly (BPMEA), achieving a high FE of 82.6 % for CO at 100 mA/cm2 and a high CO2 utilization efficiency of 87.8 %. Notably, the CO2RR selectivity, carbon utilization efficiency and long-term stability of PF-CoTAPc in BPMEA outperform reported BPM systems. We attribute the enhancement to the stable cationic shield in the double layer and suppression of proton migration, ultimately inhibiting the undesired hydrogen evolution and improving the CO2RR selectivity. Techno-economic analysis shows the least energy consumption (957 kJ/mol) for the PF-CoTAPc catalyst in BPMEA. Our findings provide a viable strategy for designing efficient CO2RR catalysts in acidic environments.

Ni Single Atoms Embedded in Graphene Nanoribbon Sieves for High-Performance CO2 Reduction to CO.

Ni single-atom catalysts (SACs) are appealing for electrochemical reduction CO2 reduction (CO2 RR). However, regulating the balance between the activity and conductivity remains a challenge to Ni SACs due to the limitation of substrates structure. Herein, the intrinsic performance enhancement of Ni SACs anchored on quasi-one-dimensional graphene nanoribbons (GNRs) synthesized is demonstrated by longitudinal unzipping carbon nanotubes (CNTs). The abundant functional groups on GNRs can absorb Ni atoms to form rich Ni-N4 -C sites during the anchoring process, providing a high intrinsic activity. In addition, the GNRs, which maintain a quasi-one-dimensional structure and possess a high conductivity, interconnect with each other and form a conductive porous framework. The catalyst yields a 44 mA cm-2 CO partial current density and 96% faradaic efficiency of CO (FECO ) at -1.1V vs RHE in an H-cell. By adopting a membrane electrode assembly (MEA) flow cell, a 95% FECO and 2.4V cell voltage are achieved at 200 mAcm-2 current density. This work provides a rational way to synthesize Ni SACs with a high Ni atom loading, porous morphology, and high conductivity with potential industrial applications.

Tin(II)-Based Metal-Organic Frameworks Enabling Efficient, Selective Reduction of CO2 to Formate under Visible Light.

Certain metal complexes are known as high-performance CO2 reduction photocatalysts driven by visible light. However, most of them rely on rare, precious metals as principal components, and integrating the functions of light absorption and catalysis into a single molecular unit based on abundant metals remains a challenge. Metal-organic frameworks (MOFs), which can be regarded as intermediate compounds between molecules and inorganic solids, are potential platforms for the construction of a simple photocatalytic system composed only of Earth-abundant nontoxic elements. In this work, we report that a tin-based MOF enables the conversion of CO2 into formic acid with a record high apparent quantum yield (9.8 % at 400 nm) and >99 % selectivity without the need for any additional photosensitizer or catalyst. This work highlights a new MOF with strong potential for photocatalytic CO2 reduction driven by solar energy.

Transition metal doped pyrrole-NC for high-performance CO2 reduction reaction to C1 products

The electrochemical CO2 reduction reaction (CO2RR) provides a potential to mitigate excessive carbon emission and achieve carbon neutrality eventually. Herein, 26 transition metal anchored pyrrole nitrogen doped carbon catalysts (TM-NCs) were proposed as high-performance single atom catalysts (SACs) for CO2RR via a multi-level screening. The results revealed that 23 out of the 26 TM-NCs possessed superior thermodynamic and electrochemical stability, and 11 TM-NCs exhibited preferred CO2RR selectivity over the side reactions. The reaction pathways of CO2RR to C1 products, including CO, HCOOH, CH3OH, and CH4, on TM-NCs were explored. Considering the activity and product selectivity along CO2RR, Cr/Mn/Co-NCs were screened out as outstanding SACs in CO2RR to HCOOH with low limiting potentials of − 0.18 to − 0.10 V, which surpassed most previously reported SACs. With the applied potentials over − 0.6 V, Cr/Mn/Co-NCs exhibited the advantages of yielding high-throughput reaction products of CH4. The coordinated N-type analysis demonstrated that compared with pyridine-type TM-NCs, pyrrole-type TM-NCs possessed weaker binding strengths with intermediates but better or comparable CO2RR activity. The results of this work highlighted pyrrole-type Cr/Mn/Co-NCs as ideal SACs for CO2RR and uncovered the effect of coordinated N-type in TM-NCs on CO2RR performance.

Assembly of highly efficient overall CO2 + H2O electrolysis cell with the matchup of CO2 reduction and water oxidation catalyst.

The exploitation of highly active and stable catalysts for reduction of CO2 and water oxidation is one of the approaches to facilitate scalable and sustainable CO2 reduction potentially at the industrial scale. Herein, a feasible strategy to rationally build an overall CO2 + H2O electrocatalytic reaction device is the preparation and matchup of a high-performance CO2 reduction catalyst and low-cost and highly active oxygen anode catalyst. A heterostructured nanosheet, γ-NiOOH/NiCO3/Ni(HCOO)2, exhibited superior catalytic activity in the oxygen evolution reaction, and was integrated with CoPc/Fe-N-C to build an overall CO2 + H2O cell with a current density of 10 mA cm-2 at a very low cell voltage of 1.97 V, and the faradaic deficiency of CO2 to CO was maintained at greater than 90% at 1.9 V.

Research Progress in High-Throughput Screening of CO2 Reduction Catalysts

The conversion and utilization of carbon dioxide (CO2) have dual significance for reducing carbon emissions and solving energy demand. Catalytic reduction of CO2 is a promising way to convert and utilize CO2. However, high-performance catalysts with excellent catalytic activity, selectivity and stability are currently lacking. High-throughput methods offer an effective way to screen high-performance CO2 reduction catalysts. Here, recent advances in high-throughput screening of electrocatalysts for CO2 reduction are reviewed. First, the mechanism of CO2 reduction reaction by electrocatalysis and potential catalyst candidates are introduced. Second, high-throughput computational methods developed to accelerate catalyst screening are presented, such as density functional theory and machine learning. Then, high-throughput experimental methods are outlined, including experimental design, high-throughput synthesis, in situ characterization and high-throughput testing. Finally, future directions of high-throughput screening of CO2 reduction electrocatalysts are outlooked. This review will be a valuable reference for future research on high-throughput screening of CO2 electrocatalysts.

Constructing surface vacancy to activate the stuck MXenes for high-performance CO2 reduction reaction

Due to the superior metallic conductivity, enhanced hydrophilic property, and large surface area, MXene has become a well-acknowledged revolutionary 2D material and may exhibit great potentials in CO2 reduction reaction (CO2RR). Herein, Mo2C, Mo2CO2, single O vacancy Mo2CO2 (Mo2CO2-Ov1), and adjacent two O vacancy Mo2CO2 (/Mo2CO2-Ov2) were employed as probes to explore the vacancy effect of surface termination on MXenes towards the catalytic performances for CO2RR. Results showed that O vacancies were readily formed on Mo2CO2, leading to the formation of O-vacancy Mo2CO2 which possessed fair thermodynamic stability and preserved the electronic feature of Mo2C near Fermi level. The exposed dz2, dxz, and dyz orbitals of Mo around 1.70 eV benefited to CO2 stabilization and activation. Mo2CO2-Ov1 exhibited considerable activity toward CH4 and CO, while Mo2CO2-Ov2 performed superior activity and selectivity toward CH4 at a low applied potential of − 0.31 V, surpassing most MXenes and Cu catalysts. The stuck Mo2CO2 could thus be effectively activated for high-performance CO2RR via surface O vacancy construction. This work discovered MXene materials as potential CO2RR catalysts and highlighted the significant promotion effect by constructing surface vacancy on MXene catalytic performances.

Rare earth praseodymium-based single atom catalyst for high performance CO2 reduction reaction

Rare earth single-atom catalysts (SACs) can be used to obtain atomically dispersed species on supports to provide the maximum number of well-defined active sites, which would subsequently maximize the utilizationof rare earth metals. However, the design and synthesis of SACs are mostly based on transition metals, and rare earth SACs have been rarely explored. Herein, we report a rare earth praseodymium SAC dispersed on a porous carbon substrate by utilizing the cascade anchoring strategy, with a metal loading of up to 5.07 wt%. This praseodymium SAC exhibits excellent catalytic performance for the electrochemical CO2 reduction reaction (CO2RR) and achieves high selectivity for CO, with a faradaic efficiency (FECO) of up to 93% at a low potential of −0.43 V vs RHE. Experiments and theoretical calculations confirm that the isolated praseodymium atoms on the substrate are critical for improving the CO2RR performance of the material.

Triple-atom catalysts 3TM-GYs (TM = Cu, Fe, and Co; GY = graphyne) for high-performance CO2 reduction reaction to C1 products

Atomically dispersed catalysts are promising materials for alleviating greenhouse effect and reproducing valuable chemical products through electrochemical CO2 reduction reaction (CO2RR). Here, earth-abundant triple transition metals (TM = Cu, Fe, and Co) anchored on graphyne (3TM-GY) were evaluated in CO2RR to C1 products by using density functional theory. Structural analyses showed that 3TM-GYs had high cohesive energy ranging from 6.91 to 6.98 eV/atom, and large binding energy ranging from 2.28 to 5.95 eV, guaranteeing structural stability in CO2RR. Electronic structure analyses confirmed the evident orbital overlap and large charge transfer between the triple TM atoms and direct-connected C atoms. The unique triangular TM trimer on GY facilitated the “point-to-point” activation of CO2 with large adsorption energy and distinctly bent configuration, providing a favorable adsorption and initial activation environment in CO2RR. 3Cu-GY exhibited a prior CO2 reduction product of CH4 with a low limiting potential of −0.41 V and high selectivities over other C1 products of 102 – 108, which surpassed the vast majority of atomically dispersed electrocatalysts. When applied potential was increased, CO2RR on 3Cu-GY had a great advantage in the high-throughput reaction processes toward HCOOH and CH4, whereas that on 3Fe-GY/3Co-GY had a great advantage toward high-reduction degree products of CH3OH and CH4. Moreover, hydrogen evolution reaction was severely inhibited, and CO2RR exhibited an overwhelming advantage over HER. This work demonstrated that graphyne was a suitable substrate material for constructing favorable coordination environment anchoring triple atom, and highlighted the advance of triple-atom catalysts for high-performance CO2RR.

Construction of frustrated Lewis pairs on TiO2-x derived from perovskite for enhanced photocatalytic CO2 reduction

Exploring high-efficiency photocatalysts to promote CO2 reduction into high value-added products is of great significance. However, the weak adsorption and activation ability for CO2 hampers the efficiency of photocatalytic CO2 reduction. Herein, hierarchical hollow TiO2-x boxes with frustrated Lewis pairs (FLPs) are successfully fabricated by in situ topological transformation of perovskite microcubes. The FLPs on TiO2-x surface are constructed with the OVs (Lewis acid sites) and its proximal surface hydroxyls (Lewis base sites). TiO2-x hollow boxes with FLPs show an excellent CO production rate (65.1 μmol g-1h−1) in pure water without any sacrificial agents or cocatalysts, which is 19.1 times and 36.6 times higher than those of TiO2 without FLPs and commercial TiO2 P25, respectively. This work presents a novel strategy to construct FLPs through in situ topological transformation route and also shows great promise for the future design of high-performance CO2 reduction photocatalysts.

Single-Atom Fe Triggers Superb CO2 Photoreduction on a Bismuth-Rich Catalyst

Insufficient separation of photogenerated electron–hole and feeble CO2 activation remain the main obstacles in the access to high-performance CO2 reduction nowadays. Single-atom active sites engine...

Selective CO2 reduction towards a single upgraded product: a minireview on multi-elemental copper-free electrocatalysts

Electrocatalytic conversion of the greenhouse gas carbon dioxide to liquid fuels or upgraded chemicals is a critical strategy to mitigate anthropogenic climate change. To this end, we urgently need high-performance CO2 reduction catalysts.

Isolated Ni single atoms in nitrogen doped ultrathin porous carbon templated from porous g-C3N4 for high-performance CO2 reduction

Abstract Electrochemical reduction of CO2 to value-added products is an effective approach to manage the global carbon balance. However, the lack of effective electrocatalyst for CO2 reduction process is a major obstacle for its development. Currently, constructing atomically dispersed non-precious metal electrocatalysts presents a promising way to build high-performance and cost-effective electrochemical CO2 reduction systems. Herein we demonstrate a novel strategy to realize the anchoring and stabilization of isolated Ni atoms in the nitrogen-doped ultrathin porous carbon nanosheets via a polydopamine-assisted g-C3N4 template method. Benefitting from the abundant atomic Ni sites and ultrahigh specific surface area of porous 2D supports (>1000 m2 g−1), the catalyst exhibits excellent activity for CO2 reduction with particularly high selectivity towards CO, achieving a faradaic efficiency of 96% at −0.86 V (vs. RHE) with a current density of 26.4 mA cm−2 in 0.1 M KHCO3 solution.

Catalysis Selects Its Own Favorite Facets

Catalytic performance of metal nanocrystals in many reactions is determined by their exposed facets. In a recent issue of Joule, Cui and colleagues report a novel self-selective strategy that utilizes CO2 electroreduction itself to smartly pick up the best catalytic facets for producing high-performance CO2 reduction catalysts.

Supported Cobalt Polyphthalocyanine for High-Performance Electrocatalytic CO2 Reduction

Summary Electrochemical reduction of CO 2 represents a possible solution for transforming atmospheric CO 2 to value-added chemicals such as CO or hydrocarbons, but so far it has been hampered by the lack of suitable electrocatalysts. In this work, we design a type of organic-inorganic hybrid material by template-directed polymerization of cobalt phthalocyanine on carbon nanotubes for a high-performance CO 2 reduction reaction. Compared with molecular phthalocyanines, the polymeric form of phthalocyanines supported on the conductive scaffold exhibits an enlarged electrochemically active surface area and improved physical and chemical robustness. Experimental results show that our hybrid electrocatalyst can selectively reduce CO 2 to CO with a large faradic efficiency (∼90%), exceptional turnover frequency (4,900 hr −1 at η = 0.5 V), and excellent long-term durability. These metrics are superior to those of most of its organic or inorganic competitors. Its high electrocatalytic activity is also supported by density functional theory calculations.