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La1–xSrxCoO3 (x = 0, 0.1, 0.2) and LaCo0.8Fe0.2O3 perovskite nanoparticles were synthesized by spray-flame synthesis, and their electrocatalytic water oxidation activity was evaluated in the prepared state. Highly crystalline, rhombohedrally distorted cubic structures of the cobaltite perovskites were confirmed by STEM and XRD analyses. The decreased JT distortions were observed in the cobaltite perovskite structure upon substitution with Sr, while orthorhombic distortions in Fe-substituted perovskites could explain the changes in their Raman spectra. Debye–Waller factors and coordination numbers from fitted EXAFS data indicate more disordered crystalline structures upon Sr substitution and a lower Co–O coordination number at 20 at% Sr. Thermal characterization of the catalysts by STA coupled with QMS shows higher mass losses in Sr-substituted catalysts, and these results were associated with a higher concentration of carbonate species in these catalysts, which was also confirmed by XPS measurements. Both Fe and Sr substitution lead to higher catalytic OER activity of the cobaltite perovskites with lower overpotentials of about 30–50 mV. The cobaltite perovskite catalyst substituted with 20 at% Sr exhibited the highest OER activity and stable electrocatalytic performance at moderate conditions.

Carbon-based electrocatalysts for oxygen reduction reaction (ORR) are prepared by a direct pathway including a two-step thermal treatment process applied to porous spheres of natural biopolymer blends. Cellulose blends with chitosan are first thermally treated at moderate temperatures (e.g., 200 °C), then pyrolyzed at elevated temperature (800–1000 °C), both steps under a constant nitrogen flow. By blending of cellulose with chitosan, the nitrogen content in the final carbon-based catalyst can be considerably increased. The influence of the composition of the precursor biopolymer blend on the ORR electrocatalytic activity is analyzed in correlation with the elemental composition and other structural features of the catalyst. The polymer blend containing cellulose:chitosan = 75:25, thermally treated 1 h at 200 °C and pyrolyzed 1 h at 800 °C under nitrogen atmosphere, shows the highest electrocatalytic ORR activity. This is attributed to an increased surface area combined with relatively high nitrogen content and a higher pyridinic/pyrrolic species ratio.

The glycerol oxidation reaction (GOR) has high potential in substituting the oxygen evolution reaction (OER) in electrochemical water splitting, enabling the synthesis of value-added organic products. The Cu-rich Cu−Co hydroxycarbonates show high activity in GOR and promote formate production but undergo severe Cu leaching in the presence of deprotonated glycerol. In this work, the electrooxidation of solketal (SOR), acetal-protected glycerol, is explored over a series of Cu−Co hydroxycarbonates, to promote the formation of glycerol-derived C3 products, such as glyceric acid, with faradaic efficiencies of around 70 %, and to limit the Cu leaching from the catalyst. The competition between OER and SOR was evaluated using rotating disk electrodes and differential electrochemical mass spectrometry. Insights into the solketal de-acetalization as a function of potential are obtained using in situ spectroscopic methods. The solketal/OH− ratio influences the reaction selectivity, with oxalate production increasing when 7 m KOH is used instead of 1 m KOH.

Developing highly efficient and selective electrocatalysts for the CO2 reduction reaction to produce value-added chemicals has been intensively pursued. We report a series of Cux Oy Cz nanostructured electrocatalysts derived from a Cu-based MOF as porous self-sacrificial template. Blending catalysts with polytetrafluoroethylene (PTFE) on gas diffusion electrodes (GDEs) suppressed the competitive hydrogen evolution reaction. 25 to 50 wt % teflonized GDEs exhibited a Faradaic efficiency of ≈54 % for C2+ products at -80 mA cm-2 . The local OH- ions activity of PTFE-modified GDEs was assessed by means of closely positioning a Pt-nanoelectrode. A substantial increase in the OH- /H2 O activity ratio due to the locally generated OH- ions at increasing current densities was determined irrespective of the PTFE amount.

Electroreduction of CO2 to multi-carbon products has attracted considerable attention as it provides an avenue to high-density renewable energy storage. However, the selectivity and stability under high current densities are rarely reported. Herein, B-doped Cu (B-Cu) and B-Cu-Zn gas diffusion electrodes (GDE) were developed for highly selective and stable CO2 conversion to C2+ products at industrially relevant current densities. The B-Cu GDE exhibited a high Faradaic efficiency of 79 % for C2+ products formation at a current density of -200 mA cm-2 and a potential of -0.45 V vs. RHE. The long-term stability for C2+ formation was substantially improved by incorporating an optimal amount of Zn. Operando Raman spectra confirm the retained Cu+ species under CO2 reduction conditions and the lower overpotential for *OCO formation upon incorporation of Zn, which lead to the excellent conversion of CO2 to C2+ products on B-Cu-Zn GDEs.

The electrocatalytic activity concerning the hydrogen evolution reaction (HER) of micrometer-sized MoS

Owing to their intrinsic amplifying effect together with their temporal resolution, field-effect transistors (FETs) are gaining momentum for the detection of different biomolecules at ultralow concentration levels such as, for example, neurotransmitters, particularly if the concentration level of the analyte is below the detection limit of commonly used electrochemical sensing methods. We demonstrate the fabrication of a spearhead reduced graphene oxide (rGO)-based FET. The fabrication of the rGO-based FET by means of an electrochemical pulse deposition technique enables a controllable process including both the deposition and reduction of the deposited graphene oxide between two carbon nanoelectrodes to form the channel of the rGO-based FET. While using double-barrel carbon nanoelectrodes, the as-produced FETs offer new possibilities in terms of their applicability in very small volumes as well as the option of being positioned close to the desired measurement region. The fabrication process was evaluated and optimized to obtain rGO-based FETs with high performance. The as-fabricated devices were evaluated in terms of sensitivity and selectivity towards dopamine. The tested devices not only showed high sensitivity towards dopamine with a linear response ranging from 1 nM to 1μM, but also maintained a similar sensing performance in the presence of 500 μM ascorbic acid.

Cost is a major drawback that limits the industrial‐scale hydrogen production through water electrolysis. The overall cost of this technology can be decreased by coupling the electrosynthesis of value‐added chemicals at the anode side with electrolytic hydrogen generation at the cathode. This Minireview provides a directory of anodic oxidation reactions that can be combined with cathodic hydrogen generation. The important parameters for selecting the anodic reactions, such as choice of catalyst material and its selectivity towards specific products are elaborated in detail. Furthermore, various novel electrolysis cell architectures for effortless separation of value‐added products from hydrogen gas are described., An ode to cheapness: This Minireview focuses on the aspects of making the electrolytic hydrogen production more cost efficient. Several anodic oxidation reactions with value‐added products are reviewed that can replace the anodic oxygen evolution reaction. The choice of electrocatalysts, increasing reaction selectivity as well as possible cell architectures are elaborated in detail.

NiyP emerged as a highly active precatalyst for the alkaline oxygen evolution reaction where structural changes play a crucial role for its catalytic performance. We probed the chemical stability o...

Mitigating high energy costs related to sustainable H2 production via water electrolysis is important to make this process commercially viable. Possible approaches are the investigation of low cost, highly active oxygen evolution reaction OER catalysts and the exploration of alternative anode reactions, such as the electrocatalytic isopropanol oxidation reaction iPOR or the glycerol oxidation reaction GOR , offering the possibility of simultaneously lowering the anodic overpotential and generating value added products. A suitable class of catalysts are non noble metal based perovskites with the general formula ABO3, featuring rare earth metal cations at the A and transition metals at the B site. We synthesised a series of LaFe1 xCoxO3 materials with x 0 0.70 by automated co precipitation at constant pH and subsequent calcination at 800 amp; 8201; C. X ray diffraction studies revealed that the phase purity was preserved in samples with x amp; 8804;0.3. The activity towards the OER, iPOR, and GOR was investigated by rotating disk electrode voltammetry, showing a relation between structure and metal composition with the activity trends observed for the three reactions. Additionally, GOR product analysis via high performance liquid chromatography HPLC was conducted after 24 and 48 amp; 8197;h electrolysis in a circular flow through cell setup, pointing out a trade off between activity and selectivity

Electrocatalytic oxidation of glycerol GOR as the anode reaction in water electrolysis facilitates the production of hydrogen at the cathode at a substantially lower cell voltage compared with the oxygen evolution reaction. It simultaneously provides the basis for the production of value added compounds at the anode. We investigate earth abundant transition metal oxide nanoparticles Fe, Ni, Mn, Co embedded in multiwalled carbon nanotubes as GOR catalysts. Out of the four investigated composites, the Ni based catalyst exhibits the highest catalytic activity toward the GOR according to rotating disk electrode voltammetry, reaching a current density of 10 mA cm 2 already at 1.31 V vs RHE, a potential below the formation of Ni3 . Chronoamperometry conducted in a flow through cell followed by HPLC analysis is used to identify and quantify the GOR products over time, revealing that the applied potential, electrolyte concentration, and duration of the experiment impact strongly the composition of the products mixture. Upon optimization, the GOR is directed toward oxalate production. Moreover, oxalate is not further converted and hence accumulates as a major organic product under the chosen conditions in a concentration ratio of 60 1 with acetate as a minor product after 48 h electrolysis in 7 M KOH, which represents a promising route for the synthesis of this highly valued product

Bimetallic tandem catalysts have emerged as a promising strategy to locally increase the CO flux during electrochemical CO2 reduction, so as to maximize the rate of conversion to C−C-coupled products. Considering this, a novel Cu/C−Ag nanostructured catalyst has been prepared by a redox replacement process, in which the ratio of the two metals can be tuned by the replacement time. An optimum Cu/Ag composition with similarly sized particles showed the highest CO2 conversion to C2+ products compared to non-Ag-modified gas-diffusion electrodes. Gas chromatography and in-situ Raman measurements in a CO2 gas diffusion cell suggest the formation of top-bound linear adsorbed *CO followed by consumption of CO in the successive cascade steps, as evidenced by the increasingνC−H bands. These findings suggest that two mechanisms operate simultaneously towards the production of HCO2H and C−C-coupled products on the Cu/Ag bimetallic surface.

Discovery of new catalysts is crucial for future growth and development of environmentally friendly energy conversion processes e. g. the production of hydrogen by water electrolysis. We developed an aerosol-based synthesis technique as a comparatively fast and facile method to prepare multi-metal catalysts. 22 different quinary metal compositions were synthesized and investigated with respect to their activity for the oxygen evolution (OER) and the glycerol oxidation (GOR) reactions. The impact of the element composition and the homogeneous distribution of the elements in the particles on catalytic performance were evaluated. The highest activity for OER was found for \(Co_{20}Cu_{20}Ni_{20}Fe_{20}Zn_{20}\). For GOR, Ag-containing catalysts were the most active, however, in most cases Ag was locally enriched and not homogeneously mixed with the other metals in the particles. Ag-based catalysts outperformed similar compositions containing one or more noble metals. The GOR selectivity of selected catalysts during long-term electrolysis was also investigated and it was shown that varying the catalyst composition via aerosol-based synthesis is a potential way to modulate the GOR selectivity.

Mixed Cu-Co hydroxycarbonates of the type (Cu₁–ₓCoₓ)₂CO₃(OH)₂ have been synthesized over the whole range of Cu-Co substitution (0≤x≤1) by co-precipitation and their electrocatalytic activity in the oxidation reactions of ethanol (EOR), ethylene glycol (EGOR) and glycerol (GOR) in alkaline environment was evaluated to retrieve composition–activity correlations. Generally, cobalt incorporation led to higher activities for the alcohol oxidation (AOR) compared to the Cu-only material and the results are compared with the competing oxygen evolution reaction (OER). On the Cu-Co hydroxycarbonates, the electrooxidation of vicinal alcohols such as glycerol and ethylene glycol requires lower overpotentials than EOR and OER. Cu leaching from the hydroxycarbonate structure was observed in the presence of vicinal alcohols. The impact of chemical and electrochemical leaching of copper from the catalysts has been studied. The chemically leached catalyst was found to show increased AOR activity compared to other hydroxycarbonates, enabling the formation of larger amounts of formic acid during GOR measured in a circular flow cell electrolyzer. The results highlight that Cu-Co hydroxycarbonates can be used as precursors to generate electrocatalytically active materials from Cu-Co hydroxycarbonates for the AOR in alkaline solution.

The electrocatalytic activity for the oxygen evolution reac-tion in alkaline electrolyte of hexagonal spinel Co3O4 nanoparticles derived using scanning electrochemical cell microscopy (SECCM) is correlated with scanning electron microscopy and atomic force microscopy images of the droplet landing sites. A unique way to deconvolute the intrinsic catalytic activity of individual crystal facets of the hexagonal Co3O4 spinel particle is demonstrated in terms of the turnover frequency (TOF) of surface Co atoms. The top surface expo-sing 111 crystal planes displayed a thickness-dependent TOF with a TOF of about 100 s-1 at a potential of 1.8 V vs RHE and a particle thickness of 100 nm. The edge of the particle exposing (110) planes, however, showed an average TOF of 270 ± 68 s-1 at 1.8 V vs RHE and no correlation with particle thickness. However, the higher atomic density of Co atoms on the edge surface (2.5 times of the top) renders the overall catalytic activity of the edge planes significantly higher than that of the top planes. The use of a free-diffusing Os- complex in the alkaline electrolyte revealed the low electrical conductivity through individual particles which explains the thickness-dependent TOF of the top planes and could be a reason for the low activity of the top (111) planes.

Alloy nanoparticles offer the possibility to tune functional properties of nanoscale structures. Prominent examples of tuned properties are the local surface plasmon resonance for sensing applications and adsorption energies for applications in catalysis. Laser synthesis of colloidal nanoparticles is well suited for generating alloy nanoparticles of desired compositions. Not only bulk alloys but also compacted mixtures of single-metal micropowders can serve as ablation targets. However, it is still unknown how mixing of the individual metals transfers from the micro- to the nanoscale. This work experimentally contributes to the elucidation of the mixing processes during the laser-based synthesis of alloy nanoparticles. Key parameters, such as the initial state of mixing in the ablation target, the laser pulse duration, the laser spot size, and the ablation time, are varied. Experiments are performed on a cobalt-iron alloy, relevant for application in oxidation catalysis, in ethanol. The extent of mixing in the targets after ablation and in individual nanoparticles are studied by energy-dispersive X-ray spectroscopy and by cyclic voltammetry at relevant conditions for the oxygen evolution reaction, as model reaction. The results point at the benefits of well pre-mixed ablation targets and longer laser pulse durations for the laser-based synthesis of alloy nanoparticles. Graphical abstract

Discovery of new electrocatalysts requires the combination of high-throughput synthesis and high-throughput screening techniques to explore the vast compositional range of compositionally complex solid solutions (CCSS).

Despite outstanding accomplishments in catalyst discovery, finding new, more efficient, environmentally neutral, and noble metal-free catalysts remains challenging and unsolved. Recently, complex solid solutions consisting of at least five different elements and often named as high-entropy alloys have emerged as a new class of electrocatalysts for a variety of reactions. The multicomponent combinations of elements facilitate tuning of active sites and catalytic properties. Predicting optimal catalyst composition remains difficult, making testing of a very high number of them indispensable. We present the high-throughput screening of the electrochemical activity of thin film material libraries prepared by combinatorial co-sputtering of metals which are commonly used in catalysis (Pd, Cu, Ni) combined with metals which are not commonly used in catalysis (Ti, Hf, Zr). Introducing unusual elements in the search space allows discovery of catalytic activity for hitherto unknown compositions. Material libraries with very similar composition spreads can show different activities vs. composition trends for different reactions. In order to address the inherent challenge of the huge combinatorial material space and the inability to predict active electrocatalyst compositions, we developed a high-throughput process based on co-sputtered material libraries, and performed high-throughput characterization using energy dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (SEM), X-ray diffraction (XRD) and conductivity measurements followed by electrochemical screening by means of a scanning droplet cell. The results show surprising material compositions with increased activity for the oxygen reduction reaction and the hydrogen evolution reaction. Such data are important input data for future data-driven materials prediction.

Bimetallic tandem catalysts have emerged as a promising strategy to locally increase the CO flux during electrochemical CO

In this work, the advantages of carbon nanoelectrodes (CNEs) and orgonic electrochemical transistors (OECTs) were merged to realise nanometre-sized, spearhead OECTs based on single- and double-barrel CNEs functionalised with a conducting polymer film. The needle-type OECT shows a high aspect ratio that allows its precise positioning by means of a macroscopic handle and its size is compatible with single-cell analysis. The device was characterised with respect to its electrolyte-gated behaviour and was employed as electrochemical sensor for the proof-of-concept detection of dopamine (DA) over a wide concentration range (10−12—10−6 M). Upon application of fixed drain and gate voltages (Vd = − 0.3 V, Vg = − 0.9 V, respectively), the nano-sized needle-type OECT sensor exhibited a linear response in the low pM range and from 0.002 to 7 μM DA, with a detection limit of 1 × 10−12 M.

Scanning electrochemical cell microscopy (SECCM) is increasingly applied to determine the intrinsic catalytic activity of single electrocatalyst particle. This is especially feasible if the catalyst nanoparticles are large enough that they can be found and counted in post-SECCM scanning electron microscopy images. Evidently, this becomes impossible for very small nanoparticles and hence, a catalytic current measured in one landing zone of the SECCM droplet cannot be correlated to the exact number of catalyst particles. We show, that by introducing a ruler method employing a carbon nanoelectrode decorated with a countable number of the same catalyst particles from which the catalytic activity can be determined, the activity determined using SECCM from many spots can be converted in the intrinsic catalytic activity of a certain number of catalyst nanoparticles.

Complex solid solutions (“high entropy alloys” with a single solid-solution phase) hold great promise in electrocatalysis because of their nearly unlim- ited number of different active sites exposed at the surface. It has been shown by theoretical studies that multiple arrangements of different elements directly neighboring a binding site create millions of differently active catalytic sites. We report a zooming-in approach using scanning electrochemical cell microscopy (SECCM) to distinguish between the averaged electrochemical response of mul- tiple active sites and active site-specific electrochemical response. Using a thin film complex solid solution electrocatalyst and a range of SECCM single bar- rel capillaries with diameters from 1.2 µm to 50 nm, we observed an averaged electrochemical response for the oxygen reduction reaction with minor statisti- cal variations for the larger capillary diameters. In contrast, significant statistical heterogeneity among the measured spots is observed for small capillary diame- ters. This statistical heterogeneity is attributed to the ability of the smaller probe size to address a comparatively smaller number of active sites with high or low activity dominating the measured electrocatalytic currents. &nbsp

Poly(propylene fumarate) (PPF) is a linear unsaturated polyester which has been widely investigated for tissue engineering due to its good biocompatibility and biodegradability. In order to extend the range of possible applications and enhance its mechanical properties, current approaches consist in the incorporation of various fillers or obtaining blends with other polymers. In the current study we designed a reinforcing agent based on carboxylated graphene oxide (GO-COOH) grafted with 2-hydroxyethyl methacrylate (GO@HEMA) for poly(propylene fumarate)/poly(ethylene glycol) dimethacrylate (PPF/PEGDMA), in order to enhance the nanofiller adhesion and compatibility with the polymer matrix, and in the same time to increase the crosslinking density. The covalent modification of GO-COOH was proved by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Raman spectroscopy. The mechanical properties, water uptake capacity, morphology, biodegradability, mineralization and in vitro cytotoxicity of PPF/PEGDMA hybrid materials containing GO@HEMA were investigated. A 14-fold increase of the compressive modulus and a 2-fold improvement in compressive strength were observed after introduction of the nanofiller. Moreover, the decrease in sol fraction and solvent swelling in case of the hybrid materials containing GO@HEMA suggests an increase of the crosslinking density. SEM images illustrate an exfoliated structure at lower nanofiller content and a tendency for agglomeration at higher concentrations. Finally, the synthesized hybrid materials proved non-cytotoxic to murine pre-osteoblast cells and induced the formation of hydroxyapatite crystals under mineralization conditions.

A novel spectroelectrochemical ATR-FTIR thin-film cell was designed and applied to elucidate the intermediates during electrocatalytic alcohol oxidation. In the novel cell design, the working electrode is positioned coplanar above the internal reflection element (IRE) to ensure uniform electrolyte film thickness at reaction conditions. The depletion of the reactant (i.e., ethanol or ethylene glycol in the case of electrocatalytic alcohol oxidation) is decreased by a specifically designed flow-through glassy carbon borehole electrode embedded in PEEK. The electrolyte can be pumped through the disk-shaped gap between the ring working electrode and the IRE into the borehole via an external peristaltic pump. To ensure a radially uniform electrolyte flow, the working electrode and the internal reflection element need to be aligned in parallel at a well-controlled distance, which was achieved by a three-microelectrode-assisted tilt correction. Tilt correction of this four-electrode ensemble and the IRE was performed by three step-motor-driven micrometer screws that allow adjustment of the electrode orientation. The effect of electrolyte pumping through the borehole electrode was analyzed by performing anodic ethanol oxidation using nickel boride as electrocatalyst. The applicability, reliability, and functionality of the cell was further assessed by oxidizing ethylene glycol and determining the reaction products as a function of the electrolyte flow rate. It is found to be essential to induce forced electrolyte convection into the thin electrolyte layer to achieve well-defined steady-state conditions, as mass transport by diffusion is by far insufficient, resulting in reactant depletion, product accumulation, and local pH changes.

Electrocatalytically active materials on the industrial as well as on the laboratory scale may suffer from chemical instability during operation, air exposure, or storage in the electrolyte. A strategy to recover the loss of electrocatalytic activity is presented. Oxygen-depolarized cathodes (ODC), analogous to those that are utilized in industrial brine electrolysis, are analyzed: the catalytic activity of the electrodes upon storage (4 weeks) under industrial process conditions (30 wt % NaOH, without operation) diminishes. This phenomenon occurs as a consequence of surface oxidation and pore blockage, as revealed by scanning electron microscopy, focused ion beam milling, X-ray photoelectron spectroscopy, and Raman spectroscopy. Potentiodynamic cycling of the oxidized electrodes to highly reductive potentials and the formation of "nascent" hydrogen re-reduces the electrode material, ultimately recovering the former catalytic activity.

The development of bifunctional oxygen electrodes is a key factor for the envisaged application of rechargeable metal-air batteries. In this work, we present a simple procedure based on pyrolysis of polybenzoxazine/metal metalloid nanoparticles composites into efficient bifunctional oxygen reduction and oxygen evolution electrocatalysts. This procedure generates nitrogen-doped carbon with embedded metal metalloid nanoparticles exhibiting high activity towards both, oxygen reduction and oxygen evolution, in 0.1 M KOH with a roundtrip voltage of as low as 0.81 V. Koutecký-Levich analysis coupled with scanning electrochemical microscopy reveals that oxygen is preferentially reduced in a 4e− transfer pathway to hydroxide rather than to hydrogen peroxide. Furthermore, the polybenzoxazine derived carbon matrix allows for stable catalyst fixation on the electrode surface, resulting in unattenuated activity during continuous alternate polarisation between oxygen evolution at 10 mA cm−2 and oxygen reduction at −1.0 mA cm−2.

Co3O4 nanocubes are evaluated concerning their intrinsic electrocatalytic activity towards the oxygen evolution reaction (OER) by means of single‐entity electrochemistry. Scanning electrochemical cell microscopy (SECCM) provides data on the electrocatalytic OER activity from several individual measurement areas covering one Co3O4 nanocube of a comparatively high number of individual particles with sufficient statistical reproducibility. Single‐particle‐on‐nanoelectrode measurements of Co3O4 nanocubes provide an accelerated stress test at highly alkaline conditions with current densities of up to 5.5 A cm−2, and allows to derive TOF values of up to 2.8×104 s−1 at 1.92 V vs. RHE for surface Co atoms of a single cubic nanoparticle. Obtaining such high current densities combined with identical‐location transmission electron microscopy allows monitoring the formation of an oxy(hydroxide) surface layer during electrocatalysis. Combining two independent single‐entity electrochemistry techniques provides the basis for elucidating structure–activity relations of single electrocatalyst nanoparticles with well‐defined surface structure., SECCM and the single‐particle‐at‐the‐tip approach are allied to gain insight into the activity of individual Co3O4 nanocube particles towards the oxygen evolution reaction. The single‐particle‐at‐the‐tip approach offers the ability to perform accelerated stress tests combined with HR‐TEM to observe structural changes of the nanoparticle during electrocatalysis at high current densities.

Electroreduction of CO2 to multi‐carbon products has attracted considerable attention as it provides an avenue to high‐density renewable energy storage. However, the selectivity and stability under high current densities are rarely reported. Herein, B‐doped Cu (B‐Cu) and B‐Cu‐Zn gas diffusion electrodes (GDE) were developed for highly selective and stable CO2 conversion to C2+ products at industrially relevant current densities. The B‐Cu GDE exhibited a high Faradaic efficiency of 79 % for C2+ products formation at a current density of −200 mA cm−2 and a potential of −0.45 V vs. RHE. The long‐term stability for C2+ formation was substantially improved by incorporating an optimal amount of Zn. Operando Raman spectra confirm the retained Cu+ species under CO2 reduction conditions and the lower overpotential for *OCO formation upon incorporation of Zn, which lead to the excellent conversion of CO2 to C2+ products on B‐Cu‐Zn GDEs., A B‐Cu gas diffusion electrode (GDE) system was developed for highly selective CO2 conversion to C2+ products at high relevant current densities by mitigating the flooding problem and tuning the three‐phase boundary. Anodic protection by sacrificial Zn nanosheets remarkably improved the long‐term stability for CO2 electroreduction at high current densities.

The modification of nickel with boron or phosphorus leads to significant enhancement of its electrocatalytic activity for the oxygen evolution reaction (OER). However, the precise role of the guest elements, B and P, in enhancing the OER of the host element (Ni) remains unclear. Herein, we present insight into the role of B and P in enhancing electrocatalysis of oxygen evolution by nickel borides and nickel phosphides. The apparent activation energy, Ea*, of electrocatalytic oxygen evolution on Ni2P was 78.4 kJ/mol, on Ni2B 65.4 kJ/mol, and on Ni nanoparticles 94.0 kJ/mol, thus revealing that both B and P affect the intrinsic activity of nickel. XPS data revealed shifts of −0.30 and 0.40 eV in the binding energy of the Ni 2p3/2 peak of Ni2B and Ni2P, respectively, with respect to that of pure Ni at 852.60 eV, thus indicating that B and P induce opposite electronic effects on the surface electronic structure of Ni. The origin of enhanced activity for oxygen evolution cannot, therefore, be attributed to such electronic modification or ligand effect. Severe changes induced on the nickel lattice, specifically, the Ni‐Ni atomic order and interatomic distances (strain effect), by the presence of the guest atoms seem to be the dominant factors responsible for enhanced activity of oxygen evolution in nickel borides and nickel phosphides., The authors acknowledge support by the BMBF in the framework of the project “NEMEZU” (03SF0497B). SMS acknowledges funding from “Programa Internacional de Becas ”la Caixa“‐Severo Ochoa”. J.A. and S.M.S. acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and the Spanish MINECO project VALPEC (ENE2017‐85087‐C3). ICN2 acknowledges support from the Severo Ochoa Programme (MINECO, Grant no. SEV‐2013‐0295) and is funded by the CERCA Programme/Generalitat de Catalunya. Part of the present work has been performed in the framework of Universitat Autònoma de Barcelona Materials Science PhD program.