Large Current Density Research Articles

Fe-Rich Medium-Entropy Core-Shell Electrocatalyst for Hydrogen Evolution Reaction Under Large Current Density.

In response to the low stability of expensive Pt under large current, exploring the stable, efficient and cost-competitive electrocatalyst for hydrogen evolution reaction is crucial for advancing green hydrogen production. Here, a strategy relating to constructing the core-shell structure with near-zero-resistance homogeneous interface is applied to synthesize new Fe-rich medium-entropy alloy (MEA) catalyst. This low-cost sample presents both outstanding durability and catalytic activity with an overpotential of 343.6mV at 1,000mAcm-2 as well as Tafel slope of 67.6mVdec-1, respectively much lower than benchmark catalyst 20%Pt/C (416.9mV, 156.8mVdec-1) in 1.0m KOH solution. Such properties are attributed to the enhanced reactivity of surface active sites with electrons easy injection from MEA metallic core to MEO (medium entropy oxide) shell via their highly conductive homogeneous interface. In MEO layer, Fe/Ni/Co sites are identified as active centres and their high oxidation is crucial to shift themselves toward deep energy, weakening Metal─H bonding and thereby accelerating hydrogen evolution. This work not only exploits one novel electrocatalyst suitable for industrial high-current environments but also provides broad application prospects for MEA utilization.

Surface-selenization formed NiFe MOF@NiSex heterogeneous arrays for enhanced oxygen evolution and methanol electrooxidation

Designing reasonable electrocatalysts for oxygen evolution reaction (OER) is a vital issue for water splitting to hydrogen. We report a surface-selenization of NiFe MOF-74 formed NiFe MOF@NiSex arrays through the simple solvothermal method. The NiFe MOF@NiSex heterostructures greatly enhance the charge transfer and cooperativity of active sites and result in strong adsorption capacity for OH– to strongly boost the OER and MOR process. The optimized electrode shows the highly efficient catalytic activity for OER with a low onset potential of 1.31 V vs. RHE and small Tafel slopes of 38.3 mV dec−1 in alkaline media. And it shows the extremely low overpotential of 229 and 329 mV at 100 and 500 mA cm−2. Moreover, its current density can reach more than 500 mA cm−2 at the potentials of 1.645 V vs. RHE at 0.8 M methanol/1 M KOH electrolyte, and it shows very good long-term stability at large current density. This heterogeneous arrays electrocatalysts may play a positive role in energy conversion and storage process.

Insights into the Solution Processing of Non-van der Waals Boron Carbide.

Exfoliation of non-layered materials is crucial to unleash their enormous potential in wide range of applications. However, the presence of strong non-van der Waals interactions in all three dimensions makes exfoliation challenging. Boron carbide (B4C), known for its high hardness, holds great potential for diverse applications. In this work, B4C is exfoliated in 29 solvents to determine its Hansen solubility parameters (HSP) and understand the dispersion stability. The experimentally determined HSP values are 19.6, 15.3 and 15.1 MPa1/2 for dispersive interactions (δD), polar interactions (δP) and hydrogen bonding interactions (δH), respectively. Subsequently, in situ dispersion stability is analyzed qualitatively and quantitatively from the space-time resolved extinction profiles employing an analytical centrifuge. The sedimentation kinetics of B4C dispersions are analyzed using instability index, integral extinction and sedimentation velocity. B4C dispersions in solvents like ε-caprolactone, isopropyl alcohol, propylene carbonate and formamide exhibited excellent stability. Additionally, B4C nanosheets are utilized to investigate their field emission properties. These nanosheets exhibit a turn-on electric field of 3.35 V/μm at an emission current density of 1 μA cm-2, and it delivered a large emission current density of ~ 375 μA cm-2 at an applied electric field of 5.7 V/μm.

Long-Cycling, Fast-Charging Lithium Metal Batteries Enabled by Nickel-Carbon Composite Nanosheet Arrays Modified Lithium Metal Anodes.

Lithium (Li) metal anode, one of the most promising candidates for next-generation rechargeable batteries, has always suffered from uneven Li deposition/stripping. To address this issue, this work designs a novel nickel-carbon composite modified Li metal anode (FNC-NF) by carbonizing fluoride nickel hydroxide nanosheet arrays grown on nickel foam (NF). These electrochemical tests present that the conductive and lithiophilic FNC can effectively restrain the growth of Li dendrites during the cycling of Li deposition/stripping at large capacities up to 10 mAh cm-2. This result is attributed to the featured FNC composition combining a core of nickel hydroxide and a mixed coating of defective carbon and Ni nanoparticles, and the unique hierarchical morphology of the FNC-NF integrating porous NF and vertically aligned FNC nanosheets. Consequently, the FNC-NF presents a stable coulombic efficiency performance after 900 cycles with an average of 99.23% for half cells, a lifespan over 3200 h for symmetric cells at 1 mA cm-2 and 1 mAh cm-2, and a remarkable cycling stability at large current densities of up to 15 mA cm-2 at 1 mAh cm-2. Moreover, the Li||FNC-NF||LiFePO4 full cells show superior capacity retention and cycling stability at 1 C.

Highly enhanced electro-catalytic behavior of an amide functionalized Cu(II) coordination polymer on OER at large current densities

Extensive utilization of fossil fuels has led to their swift exhaustion, causing an escalating energy dilemma and significant environmental apprehensions. This situation has spurred advancement of sustainable energy conversion systems. Electrochemical water splitting is viewed as a capable method for generating hydrogen and oxygen intended for diverse electrochemical energy apparatus. A proficient, multifunctional electro-catalyst capable of facilitating both OERs) and HERs is of paramount importance. In this work, we report Cu-MOF electro-catalyst synthesized via the solvothermal route engaging OER activity using nickel foam (NF) in a 1 M KOH solution. Several analytical techniques were used to investigate the electro-catalysts BET, PXRD, FTIR and oxidation states. The water-splitting evaluation of the LOCOM-1 demonstrated exceptional oxygen activity concerning OER (oxygen evolution reaction), showcasing to extent a current density of 10 mAcm−2 a reduced of 286 mV over potential. Additionally, it exhibited a diminished onset potential of 1.37 V attributable towards a decreased Tafel slope of 44.50 mVdec−1, and a proton couple electron transfer (PCET) channel that is stable over an extended period of time (1000 cycles of cyclic voltammetry and 40 h of chronoamperometry). Therefore, this current endeavour might offer a new prospect or pathway for exploring the OER (Oxygen Evolution Reaction).

RuxMoS2 interfacial heterojunctions achieve efficient overall water splitting and stability in both alkaline and acidic media under large current density exceeding 100 mA cm-2

RuO2 has attracted considerable attention as a potential acid-alkali OER electrocatalyst. Exploring highly active Rux/MoS2@NF (x = 1, 2, 3 mmol) electrocatalysts for acidic oxygen evolution reaction (OER) is critical for advancing H2 production via water electrolysis using proton exchange membrane electrolyzer. For an alkaline current density of 10 mA cm−2, Ru2/MoS2@NF has severely low HER and OER overpotentials of -38.44 and 39.42 mV. Tafel has a smaller slope of 43.32 and 24.58 mV dec−1 and exceptional stability exceeding 600 h At 0.5 M H2SO4, Ru2/MoS2@NF at 100 mA cm−2 current density, OER is only 336.2 mV, considerably better than commercial Pt/C. In addition, doping Ru into MoO6 induces structural defects to generate oxygen vacancies, increasing the Mo6+/Mo4+ ratio. In situ Raman analyses showed that Ru doping has numerous structural defects, there was an increase in Mo−O active species at octahedral sites in Rux/MoS2, indicating accelerated generation of the key *O intermediates for enhanced OER kinetics. This work provides insight into the design of Ru based electrocatalysts that can considerably improve the performance of acidic OER, provides a roadmap for achieving efficient, economical and sustainable electrolysis of water for hydrogen production, and provides a roadmap for the design and commercialization of materials.

Electronic Structure Engineering of NiCoP Sites via N, Ru Dual Doping for Bifunctional Water Electrolysis.

Exploiting highly effective electrocatalysts is a challenge for boosting the overall efficiency of water splitting. Herein, we present a nitrogen and ruthenium dual-doping strategy to tailor the electronic structures of NiCoP(N, Ru-NiCoP), creating high-performance bifunctional electrodes for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The dual-doping approach is favorable for electronic interactions within the NiCoP and CoP, yielding a near-zero Gibbs free energy for H adsorption. Consequently, the optimized N, Ru-NiCoP electrodes exhibit exceptional bifunctional activities, with overpotentials of 53 and 405 mV at 100 mA cm-2 for the HER and OER, respectively. Notably, their performance surpasses that of commercial Pt/C and RuO2 catalysts at large current densities, demonstrating their potential for industrial water splitting applications. Moreover, the overall water-splitting device achieves a current density of 10 mA cm-2 with a driving voltage of only 1.54 V. This work provides an effective heteroatom doping strategy to develop low-cost and highly active electrocatalysts.

Coupling [Bmim]PF6 and Pd NPs Modulated MOF-Based Material for Synergetic Regulating Electrocatalytic CO2 Reduction.

Metal-organic frameworks (MOFs) with a large number of active sites and high porosity are considered to be good platforms for the carbon dioxide electroreduction reaction (CO2RR) but with confined low conductivity or low efficiency. Here, Pd-[Bmim]PF6/Cu-BTC with exceptional selectivity and electron-transfer ability is elaborately designed by introducing ionic liquids (ILs) into the MOFs. ILs favor promoting the overall current density of the catalysts, and the introduction of Pd atoms combined with O atoms on the catalyst surface reconfigures into strong Pd-O bonds, improving the desorption efficiency of *CO. The unique structure of the catalyst Pd-[Bmim]PF6/Cu-BTC leads to a significant improvement of the C1 product with a high Faraday efficiency (FE) of 99.36%, especially for carbon monoxide (CO) with an FE of 93.18% (-1.1 VRHE). The exceptional performance of the catalyst is verified by density functional theory (DFT) calculations, and the reduction of the free energy required by *HOCO as a key intermediate for CO production was only 0.12 eV, providing new insights to improve the electrocatalytic performance of MOF-based materials for the CO2RR. In this research, an effective and promising strategy that configures active sites by larger current density is proposed to enhance the efficiency of the CO2RR.

Carbon Nanocage Supported Asymmetrically Coordinated Nickle Single-Atom for Enhanced CO2 Electroreduction in Membrane Electrode Assembly.

Designing efficient catalysts for operating CO2 electroreduction in membrane electrode assembly (MEA) faces significant obstacles. Herein, we propose an asymmetrically coordinated Ni single-atom catalyst featuring axial Br coordination at NiN4Br sites anchoring onto hollow Br/N co-doped carbon nanocages, achieved through a NaBr-assisted confined-pyrolysis strategy. The Ni-NBr-C catalyst exhibits a high CO Faradaic efficiency (FECO>97 %) over the current density range of 50 to 350 mA cm-2 in the MEA device. Furthermore, Ni-NBr-C shows a stable cell voltage of 2.66±0.2 V while delivering a large current density of 350 mA cm-2 over an 85-hour long-term operation, demonstrating its potential for industrial-scale applications. Advanced characterization techniques and theoretical calculations reveal that the coordination and doping of Br not only enhance the intrinsic activity but also highlight that the unique pore structure improves mass transfer efficiency.

Carbon Nanocage Supported Asymmetrically Coordinated Nickle Single‐Atom for Enhanced CO2 Electroreduction in Membrane Electrode Assembly

AbstractDesigning efficient catalysts for operating CO2 electroreduction in membrane electrode assembly (MEA) faces significant obstacles. Herein, we propose an asymmetrically coordinated Ni single‐atom catalyst featuring axial Br coordination at NiN4Br sites anchoring onto hollow Br/N co‐doped carbon nanocages, achieved through a NaBr‐assisted confined‐pyrolysis strategy. The Ni‐NBr‐C catalyst exhibits a high CO Faradaic efficiency (FECO>97 %) over the current density range of 50 to 350 mA cm−2 in the MEA device. Furthermore, Ni‐NBr‐C shows a stable cell voltage of 2.66±0.2 V while delivering a large current density of 350 mA cm−2 over an 85‐hour long‐term operation, demonstrating its potential for industrial‐scale applications. Advanced characterization techniques and theoretical calculations reveal that the coordination and doping of Br not only enhance the intrinsic activity but also highlight that the unique pore structure improves mass transfer efficiency.

Prompting CO2 Electroreduction to Ethanol by Iron Group Metal Ion Dopants Induced Multi‐sites at the Interface of SnSe/SnSe2 p–n Heterojunction

AbstractThe development of non‐copper‐based materials for CO2 electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M2+ (M=Fe, Co, or Ni)‐doped amorphous/crystalline SnSe/SnSe2 nanorod/nanosheet hierarchical structures (a/c‐SnSe/SnSe2) for selective CO2 electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M2+‐doped SnSe/SnSe2 p‐n heterojunction, which strengthens *CO intermediate binding for further C−C coupling to eventual ethanol generation. As a representative, Fe9.0%‐a/c‐SnSe/SnSe2 exhibits an ethanol Faradaic efficiency of 62.7 % and a partial current density of 239.0 mA cm−2 at −0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5 % and a partial current density of 201.2 mA cm−2 with a full‐cell energy efficiency of 24.1 % at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non‐Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO2 electroreduction.

Prompting CO2 Electroreduction to Ethanol by Iron Group Metal Ion Dopants Induced Multi-sites at the Interface of SnSe/SnSe2 p-n Heterojunction.

The development of non-copper-based materials for CO2 electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M2+ (M=Fe, Co, or Ni)-doped amorphous/crystalline SnSe/SnSe2 nanorod/nanosheet hierarchical structures (a/c-SnSe/SnSe2) for selective CO2 electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M2+-doped SnSe/SnSe2 p-n heterojunction, which strengthens *CO intermediate binding for further C-C coupling to eventual ethanol generation. As a representative, Fe9.0%-a/c-SnSe/SnSe2 exhibits an ethanol Faradaic efficiency of 62.7 % and a partial current density of 239.0 mA cm-2 at -0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5 % and a partial current density of 201.2 mA cm-2 with a full-cell energy efficiency of 24.1 % at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non-Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO2 electroreduction.

Bamboo-Like Carbon Nanotube-Encapsulated Fe2C Nanoparticles Activate Confined Fe2O3 Nanoclusters Via d-p-d Orbital Coupling for Alkaline Oxygen Evolution Reaction.

The efficient anion exchange membrane water electrolysis is challenging with low cell voltage and long-term stability at large current density, due to the unstable anodic oxygen evolution reaction (OER). Fe-based electrocatalysts are potential candidates for the anodic OER. In Fe-based materials, iron oxides always show better stability in alkaline solution but lower OER activity. However, the catalysts in previous study are difficult to continuously and effectively activate iron oxides supported on carbon during electrocatalysis. Herein, a new class of electrocatalyst: bamboo-like carbon nanotubes (B-CNT)-encapsulated Fe2C nanoparticles (NPs) supported Fe2O3 nanoclusters (NCs), named Fe2O3/B-CNT@Fe2C is reported. Theoretical calculations and experimental results reveal that B-CNT-encapsulate Fe2C NPs activate Fe2O3 NCs by the d-p-d orbital coupling, thereby weakening the adsorption of OOH* intermediate during OER process. The electrolyzer based on the electrocatalyst requires only 1.48 V to reach 1.0 A cm-2 and shows a long-term stability at 1.0 A cm-2 for 1600 h, comparable to the best-reported values for the anion exchange membrane water electrolyzer (AEMWE).

Waxberry-like TiO2 with Synergistic Surface Modification of Pyrolytic Carbon Coating and Carbon Nanotubes as an Anode for Li-Ion Battery.

Titanium dioxide (TiO2) as an anode material for lithium-ion batteries (LIBs) has the advantages of tiny volume expansion, high operating voltage, and outstanding safety performance. However, due to the low conductivity of TiO2 and the slow diffusion rate of lithium ions (Li+), it is limited in the application of LIBs. Therefore, waxberry-like TiO2 comodified by pyrolytic carbon coating and carbon nanotubes was prepared in this work. The waxberry-like TiO2 with nanorods on its surface shortens the diffusion distance of Li+. Carbon nanotubes and waxberry-like TiO2 are tightly combined through electrostatic assembly and form a cross-linked conductive network to provide more electron transmission paths. A thin layer of pyrolytic carbon wraps carbon nanotubes and waxberry-like TiO2, which enhance the conductivity of the composites and ensure the structural integrity of the materials throughout the cycling process. The experimental data revealed that the discharge-specific capacity of TiO2@CNT@C is 170.5 mAh g-1 after 3000 cycles at a large current density of 5 A g-1, and the discharge-specific capacity is still 143 mAh g-1 at the superhigh rate of 10 A g-1, which provides excellent rate performance and cyclic stability. The efficient dual-carbon modification strategy could potentially be extended to other materials.

In-situ reconstitution of Ni(III)-based active sites from vanadium doped nickel phosphide/metaphosphate for super-stable urea-assisted water electrolysis at large current densities

Efficient bifunctional electrocatalysts towards oxygen evolution reaction (OER) and urea electrooxidation reaction (UOR) are urgently needed for hydrogen production from urea-containing wastewater electrolysis. The main challenge lies in the sluggish UOR kinetics and the stability of catalyst under practical high current density. Here, a vanadium doped heterostructure of Ni(PO3)2/Ni2P with shaggy nanosheet morphology was successfully synthesized. The doping of V atoms promotes the formation of Ni(PO3)2/Ni2P heterojunction in phosphating process. It is demonstrated that V-doped Ni(PO3)2/Ni2P accelerates the generation of real active site V@NiOOH in OER and UOR processes, which can also be stabilized by the PO3− ions. The in-situ formed V@NiOOH increases the adsorption energy of urea molecule, and reduces the adsorption energy of key intermediates *COO, thus facilitating the release of CO2 product from the catalyst surface. The energy barrier of *HNCON to *NCON is also reduced dramatically, promoting the kinetics of UOR. In addition, the shaggy nanosheets morphology provides large number of catalytic sites and transport channels, which are conducive to mass transfer under high current density. As a result, the V-Ni(PO3)2/Ni2P electrode based anion-exchange membrane (AEM) electrolyzer needs only 1.61 V to drive the total urea electrolysis at an industrial grade current density of 550 mA cm−2 with an outstanding durability of 700 h. This work paves the way for designing practical efficient and stable electrocatalyst for urea contained wastewater electrolysis to produce hydrogen.

Triplet supercurrents in lateral Josephson junctions with a half-metallic ferromagnet

In the area of superconducting spintronics, spin-triplet supercurrents in half-metallic ferromagnets (HMFs) could yield dissipationless spin transport over large distances and high current density. Promising among the HMFs is the perovskite oxide La0.7Sr0.3MnO3 (LSMO), and recent studies in combination with the high-Tc superconductor YBa2Cu3O7, or the conventional superconductor NbTi, showed long-range effects. Here we focus on two issues that as yet have received less attention: the value of the critical current in the HMF in the limit of a very small electrode distance (20 nm) and the nature of the spin-triplet generator. We use lateral junctions shaped as a bar, square, and disk, and find high supercurrent densities of the order of 1011 A/m2, pointing to an efficient triplet generation mechanism. This is surprising in the sense that no magnetic inhomogeneity is purposely built in, as is done in conventional metal triplet junctions. Furthermore, from the magnetic field dependence of the critical current interference patterns, we find a uniform supercurrent distribution in bar-shaped devices, but one more constricted to the rim in disk devices, which is an expected consequence of the geometry. We also analyze the temperature dependence of the critical current and find the quadratic dependence that was predicted in the limit of small junction lengths. From studying the NbTi/LSMO interface with scanning electron transmission microscopy, we conclude that the magnetic inhomogeneity required for triplet generation resides in the LSMO layer adjacent to the interface. Published by the American Physical Society 2024

Reducing Dead Species by Electrochemically‐Densified Cathode‐Interface‐Reaction Layer towards High‐Rate‐Endurable Zn||I‐Br Batteries

Interhalogen‐involved aqueous Zn||halogen batteries (AZHBs) are latent high‐energy systems for grid‐level energy storage, yet usually suffer from poor high‐rate endurability caused by the formation of “dead species”. Herein, via an electrochemically‐densified cathode‐interface‐reaction layer (CIRL), Zn||I‐Br batteries involving interhalogen reactions between the I2 cathode and Br‐ from the electrolytes are initially achieved with excellent high‐rate endurability. Different from that in diluted electrolytes, the CIRL formed in Br‐‐concentrated electrolyte is denser and water‐lean, which enables halogen species conversion with a more rapid charge transfer and lower activation energy. More importantly, the CIRL robustly affords a decent I2 conservation by accelerated conversion kinetics and limited species diffusion, thereby endowing the Zn||I‐Br batteries with an ultralong high‐rate lifespan. The electrochemical mechanism is sufficiently verified by multiple spectral characterizations. Consequently, Zn||I‐Br batteries in Br‐‐concentrated (20 m) electrolytes exhibit an overwhelming rate capability and lifespan to those in Br‐‐diluted (2 m) electrolytes. Typically, when cycled at a large current density of 10 A g‐1, an ultralong lifespan of over 25,000 cycles is achieved with a high retention of 98.3%. This study provides new insight into the CIRL‐dictated active species conservation for high‐rate endurable AZHBs, which could apply to other high‐energy interhalogen batteries.

Reducing Dead Species by Electrochemically-Densified Cathode-Interface-Reaction Layer towards High-Rate-Endurable Zn||I-Br Batteries.

Interhalogen-involved aqueous Zn||halogen batteries (AZHBs) are latent high-energy systems for grid-level energy storage, yet usually suffer from poor high-rate endurability caused by the formation of "dead species". Herein, via an electrochemically-densified cathode-interface-reaction layer (CIRL), Zn||I-Br batteries involving interhalogen reactions between the I2 cathode and Br- from the electrolytes are initially achieved with excellent high-rate endurability. Different from that in diluted electrolytes, the CIRL formed in Br--concentrated electrolyte is denser and water-lean, which enables halogen species conversion with a more rapid charge transfer and lower activation energy. More importantly, the CIRL robustly affords a decent I2 conservation by accelerated conversion kinetics and limited species diffusion, thereby endowing the Zn||I-Br batteries with an ultralong high-rate lifespan. The electrochemical mechanism is sufficiently verified by multiple spectral characterizations. Consequently, Zn||I-Br batteries in Br--concentrated (20 m) electrolytes exhibit an overwhelming rate capability and lifespan to those in Br--diluted (2 m) electrolytes. Typically, when cycled at a large current density of 10 A g-1, an ultralong lifespan of over 25,000 cycles is achieved with a high retention of 98.3%. This study provides new insight into the CIRL-dictated active species conservation for high-rate endurable AZHBs, which could apply to other high-energy interhalogen batteries.

Modulating Built‐In Electronic Configuration via Variable Al Doping for Robust Oxygen Evolution Reaction

Transition metal‐based electrocatalysts play a crucial role in the oxygen evolution reaction (OER). However, their heavy reliance on free electrons at the <i>d</i>‐band significantly limits the screening of potentially efficient, earth‐abundant alternatives. Despite extensive exploration of catalyst engineering through multi‐metal cooperation to modulate electron configuration by introducing additional transition metals, practical success remains elusive. Here, we present a straightforward electrodeposition method for preparing amorphous FeCoAl hydroxide catalysts. The introduction of Al contributes external free electrons, enabling a well‐defined electron configuration for intermediate adsorption. Al doping also adjusts the <i>d</i>‐band position of adjacent Co atoms, bringing them closer to the Fermi level and significantly enhancing intrinsic activity at the active sites. Furthermore, Al dopants facilitate rapid mass and charge transfer near the catalyst layer, promoting faster reaction kinetics. Leveraging these properties, the FeCoAl hydroxide catalyst achieves a large current density of 100 mA cm <sup>‐2</sup> at an overpotential of 340 mV, with a small Tafel slope of 29.1 mV dec <sup>‐1</sup>. Our work provides valuable insights for designing efficient electrocatalysts by leveraging free electron‐rich metal doping and expanding the parameter space for catalyst engineering.

Comparative Study of Different Polymeric Binders in Electrochemical CO Reduction.

Electrochemical reduction of carbon monoxide offers a possible route to produce valuable chemicals (such as acetate, ethanol or ethylene) from CO2 in two consecutive electrochemical reactions. Such deeply reduced products are formed via the transfer of 4-6 electrons per CO molecule. Assuming similar-sized CO2 and CO electrolyzers, 2-3-times larger current densities are required in the latter case to match the molar fluxes. Such high reaction rates can be ensured by tailoring the structure of the gas diffusion electrodes. Here, the structure of the cathode catalyst layer was systematically varied using different polymeric binders to achieve high reaction rates. Simple linear polymers, bearing the same backbone but different functional groups were compared to highlight the role of different structural motifs. The comparison was also extended to simple linear, partially fluorinated polymers. Interestingly, in some cases similar results were obtained as with the current state-of-the-art binders. Using different surface-wetting characterization techniques, we show that the hydrophobicity of the catalyst layer-provided by the binder- is a prerequisite for high-rate CO electrolysis. The validity of this notion was demonstrated by performing CO electrolysis experiments at high current density (1 A cm-2) for several hours using PVDF as the catalyst binder.