Selective Electrocatalysts Research Articles

Unveiling the Synergy of O‐Vacancy and Heterostructure over MoO3‐x/MXene for N2 Electroreduction to NH3

AbstractThe electrochemical N2 reduction reaction (NRR) offers a promising approach for sustainable NH3 production, and modulating the structural/electronic configurations of the catalyst materials with optimized electrocatalytic properties is pivotal for achieving high‐efficiency NRR electrocatalysis. Herein, vacancy and heterostructure engineering are rationally integrated to explore O‐vacancy‐rich MoO3‐x anchored on Ti3C2Tx‐MXene (MoO3‐x/MXene) as a highly active and selective NRR electrocatalyst, achieving an exceptional NRR activity with an NH3 yield of 95.8 µg h−1 mg−1 (−0.4 V) and a Faradaic efficiency of 22.3% (−0.3 V). A combination of in situ spectroscopy, molecular dynamics simulations and density functional theory computations is employed to unveil the synergistic effect of O‐vacancies and heterostructures for the NRR, which demonstrates that O‐vacancies on MoO3‐x serve as the active sites for N2 chemisorption and activation, while the MXene substrate can further regulate the O‐vacancy sites to break the scaling relation to effectively stabilize *N2/*N2H while destabilizing *NH2/*NH3, resulting in more optimized binding affinity of NRR intermediates toward reduced energy barriers and an enhanced NRR activity for MoO3‐x/MXene.

Exploring the Synergistic Effect of Novel Ni‐Fe in 2D Bimetallic Metal‐Organic Frameworks for Enhanced Electrochemical Reduction of CO2

AbstractThe two‐dimensional (2D) metal‐organic frameworks (MOFs) have capabilities to reduce CO2 with high Faradaic efficiency (FE). Herein, the role of incorporating bimetallic Ni and Fe into newly constructed MOFs is studied. This work highlights the use of bimetallic synergistic effect with surrounded nitrogen atoms, opening new avenues for efficient electrocatalytic reduction of CO2. This MOF Ni‐Fe contains moieties surrounded by four nitrogen atoms via covalent bonding, which resembles the porphyrin‐based molecular units as selective and effective homogeneous CO2 reduction electrocatalysts. Besides, density functional theory (DFT) also helps to figure out that the incorporation combination of metals helps achieve the high FE of 98.2% with stability up to 30 h under a low applied potential of −0.5 V versus reversible hydrogen electrode (RHE). These results offer a promising avenue to develop and optimize the MOFs‐based electrocatalysts for electrochemical conversion of CO2.

Electron fixation of Sn2+/Cu+ bimetallic catalyst on flexible carbon fiber cloth for highly converting gaseous CO2 to formate at moderate potential

Designing highly active and selective electrocatalysts for converting CO2 into value-added chemicals and fuels by electrochemical method is still a challenge. Herein, we have successfully fabricated a lotus-like morphology of Sn/Cu alloy on carbon fiber cloth via a facile electrodeposition method followed by air-dried treatment. Owing to the presence of Sn2+ and Cu+ on the surface of Sn/Cu alloy, this bimetallic Sn/Cu electrode exhibits the outstanding FE of formate with a maximum value of 95.81% at −1.07 V versus RHE, and the total current density at −0.97 V versus RHE keeping unchanged at 33.78 mA cm−2 under the 20 h electrolysis even with the replacement of electrolyte. This work provides an effective strategy for highly boosting the selective production of formate from electrochemical CO2 reduction by stabilizing the intermediate valence of bimetallic alloy.

Dynamic Restructuring of Cu‐Doped SnS2 Nanoflowers for Highly Selective Electrochemical CO2 Reduction to Formate

AbstractWith ever‐increasing energy consumption and continuous rise in atmospheric CO2 concentration, electrochemical reduction of CO2 into chemicals/fuels is becoming a promising yet challenging solution. Sn‐based materials are identified as attractive electrocatalysts for the CO2 reduction reaction (CO2RR) to formate but suffer from insufficient selectivity and activity, especially at large cathodic current densities. Herein, we demonstrate that Cu‐doped SnS2 nanoflowers can undergo in situ dynamic restructuring to generate catalytically active S‐doped Cu/Sn alloy for highly selective electrochemical CO2RR to formate over a wide potential window. Theoretical thermodynamic analysis of reaction energetics indicates that the optimal electronic structure of the Sn active site can be regulated by both S‐doping and Cu‐alloying to favor formate formation, while the CO and H2 pathways will be suppressed. Our findings provide a rational strategy for electronic modulation of metal active site(s) for the design of active and selective electrocatalysts towards CO2RR.

Dynamic Restructuring of Cu-Doped SnS2 Nanoflowers for Highly Selective Electrochemical CO2 Reduction to Formate.

With ever-increasing energy consumption and continuous rise in atmospheric CO2 concentration, electrochemical reduction of CO2 into chemicals/fuels is becoming a promising yet challenging solution. Sn-based materials are identified as attractive electrocatalysts for the CO2 reduction reaction (CO2 RR) to formate but suffer from insufficient selectivity and activity, especially at large cathodic current densities. Herein, we demonstrate that Cu-doped SnS2 nanoflowers can undergo in situ dynamic restructuring to generate catalytically active S-doped Cu/Sn alloy for highly selective electrochemical CO2 RR to formate over a wide potential window. Theoretical thermodynamic analysis of reaction energetics indicates that the optimal electronic structure of the Sn active site can be regulated by both S-doping and Cu-alloying to favor formate formation, while the CO and H2 pathways will be suppressed. Our findings provide a rational strategy for electronic modulation of metal active site(s) for the design of active and selective electrocatalysts towards CO2 RR.

Highly stable and methanol tolerant oxygen reduction reaction electrocatalyst Co/CoO/SnO@N-C nanocubes by one-step introduction of functional components

To develop high-performance non-precious metal-based electrocatalysts for oxygen reduction reaction (ORR) is an urgent demand. We herein report an ingenious strategy to develop highly selective and competitive precious metal-free ORR electrocatalyst Co/CoO/SnO encapsulated in N-rich mesoporous carbon (CCS@NPC) nanocubes, via a simple one-step introduction of all functional components. Atomically mixed composites with significantly enhanced catalytic activity were obtained by adopting amorphous mesoporous ternary metal oxides CoSnO3 nanocubes as precursor and template. The synergistic effect of the triphase nanohybrids (Co, CoO & SnO) anchored in nitrogen-doped mesoporous carbon nanocubes promoted the catalytic reactions, owning to the anisotropic morphology, great heterojunction interfaces, and structural stability. The large-scale prepared CCS@NPC exhibited excellent electrocatalytic activity toward ORR with an admirable onset potential (1.01 V) and diffusion-limited current density (5.88 mA cm−2). The CCS@NPC showed stronger stability (20 h) and higher methanol tolerance with the concentration up to 8.0 M, compared to that of commercial Pt/C.

Managing the Nitrogen Cycle via Plasmonic (Photo)Electrocatalysis: Toward Circular Economy.

As renewable energy sources are either intermittent in nature or remote in location, developing cost-effective, sustainable, modular systems and technologies to store and transport renewables at an industrial scale is imperative. Storing cheap renewable electricity into chemical bonds (i.e., chemical energy storage) could be a transformative opportunity for reliable and resilient grid energy storage. This approach enables renewables to be stored and shipped similarly to fossil fuels. Currently, the chemical industry primarily consumes fossil feedstock as an energy source, which has been the standard for over a century. A paradigm shift is required to move toward a more sustainable route for chemical synthesis by electrifying and decarbonizing the modern chemical industry. As renewable electricity costs decrease, (photo)electrosynthesis is gaining interest for synthesizing high-value and high-energy fuels and molecules in a clean, sustainable, and decentralized manner.The nitrogen cycle is one of the Earth's most critical biogeochemical cycles since nitrogen is a vital element for all living organisms. Artificial nitrogen fixation via a (photo)electrochemical system powered by renewables provides an alternative route to resource- and carbon-intensive thermochemical processes. (Photo)electrochemical nitrogen fixation at a large scale necessitates the discovery of active, selective, and stable heterogeneous (photo)electrocatalysts. In addition, the use of advanced in situ and operando spectroscopic techniques is needed to pinpoint the underlying reaction mechanisms. The selectivity of nitrogen (N2) molecules on the catalyst surface and suppressing thermodynamically favorable side reactions (e.g., hydrogen evolution reaction) are the main bottlenecks in improving the rate of (photo)electrochemical nitrogen fixation in aqueous solutions. The rational design of electrode, electrolyte, and reactors is required to weaken the strong nitrogen-nitrogen triple bond (N≡N) at or near ambient conditions. This Account covers our group's recent advances in synthesizing shape-controlled hybrid plasmonic nanoparticles, including plasmonic-semiconductor and plasmonic-transition metal nanostructures with increased surface areas. The nanocatalysts' selectivity and activity toward nitrogen conversion are benchmarked in liquid- and gas-phase electrochemical systems. We leverage operando vibrational-type spectroscopy (i.e., surface-enhanced Raman spectroscopy (SERS)) to identify intermediate species relevant to nitrogen fixation at the electrode-electrolyte interface to gain mechanistic insights into reaction mechanisms, leading to the discovery of more efficient catalysts. Operando SERS revealed that the nitrogen reduction reaction (NRR) to ammonia on hybrid plasmonic-transition metal nanoparticle surfaces (e.g., Pd-Ag) occurs through an associative mechanism. In the NRR process, hydrazine (N2H4) is consumed as an intermediate species. A femtosecond pulsed laser is used to synthesize hybrid plasmonic photocatalysts with homogeneously distributed Pd atoms on a Au nanorod surface, resulting in enhanced optoelectronic and catalytic properties. The overarching goal is to develop modular photoelectrochemical systems for long-duration renewable energy storage. In the context of nitrogen fixation, we aim to propose strategies to manage the nitrogen cycle through the interconversion of N2 and active nitrogen-containing compounds (e.g., NH3, NOx), enabling a circular nitrogen economy with sustainable and positive social and economic outcomes. The versatile approaches presented in this Account can inform future opportunities in (photo)electrochemical energy conversion systems and solar fuel-based applications.

Biomass-derived amorphous carbon with localized active graphite defects for effective electrocatalytic N2 reduction

The development of highly selective and cost-effective electrocatalysts from renewable biomass for the durable electrochemical conversion of N2 to NH3 under ambient conditions is exceedingly attractive. Herein, we report on an affordable biomass pine tower (PT) - derived amorphous porous carbon with rich graphite defects as an efficient electrocatalyst for N2 fixation. Following KOH activation, the as-prepared PT nanomaterial exhibited a large specific surface area (802.69 m2 g−1) with abundant active graphite defect centers, making it a highly active catalyst for N2 reduction. Under the ambient conditions in a 0.1 M Na2SO4 electrolyte, an NH3 yield of 16.15 μg h−1 mgcat.-1 with a Faradaic efficiency of 3.69% at −0.6 V vs. a reversible hydrogen electrode (RHE) was achieved. Moreover, this catalyst exhibited excellent selectivity and electrocatalytic stability in the production of ammonia. This work provides a feasible and evolutionary strategy for accelerating the development of biomass-derived carbon catalysts for artificial N2 fixation.

Amine-Functionalized Carbon Nanodot Electrocatalysts Converting Carbon Dioxide to Methane.

The electrochemical conversion of carbon dioxide (CO2 ) to methane (CH4 ), which can be used not only as fuel but also as a hydrogen carrier, has drawn great attention for use in supporting carbon capture and utilization. The design of active and selective electrocatalysts with exceptional CO2 -to-CH4 conversion efficiency is highly desirable; however, it remains a challenge. Here a molecular tuning strategy-in situ amine functionalization of nitrogen-doped graphene quantum dots (GQDs) for highly efficient CO2 -to-CH4 conversion is presented. Amine functionalized nitrogen-doped GQDs achieve a CH4 Faradic efficiency (FE) of 63% and 46%, respectively, at CH4 partial current densities of 170 and 258mA cm-2 , approximating to or even outperforming state-of-the-art Cu-based electrocatalysts. These GQDs also convert CO2 to C2 products mainly including C2 H4 and C2 H5 OH with a maximum FE of ≈10%. A systematic analysis reveals that the CH4 yield varies linearly with amine group content, whereas the C2 production rate is positively dependent on pyridinic N dopant content. This work provides insight into the rational design of carbon catalysts with CO2 -to-CH4 conversion efficiency at the industrially relevant level.

(Invited) Design Strategies of PdCu Bimetals for Engineering Selectivity Toward Nitrogen and Ammonia from Electrochemical Nitrate Reduction

Electrochemical conversion of harmful nitrate (NO3 -) has attracted attention to produce benign dinitrogen (N2) and ammonia (NH3) fuel. The designed construction of PdCu bimetallic nanoparticles is important for developing highly efficient and selective electrocatalysts. Here, we engineered the atomic structure of Pd/Cu and controlled Cu surface coverage on Pd nanocube nanoparticle to enhance the NO3 - conversion rate and steer the selectivity of N2/NH3. Highly ordered structure of PdCu nanoparticles showed high nitrate reduction activity and excellent dinitrogen selectivity in a neutral electrolyte compared to disordered PdCu nanoparticles. We also develop Pd nanocube nanoparticles and introduce Cu metals on the surface by underpotential deposition (UPD) method. The decorated Cu metals catalyze the reduction of NO3 - to NO2 - and the Pd (100) enhances the activity and selectivity of NO2 - to N2. Rotating disk electrode (RDE) and H-cell tests were conducted for NO3 -/NO2 - reduction activity and the selectivity of PdCu bimetal electrocatalysts were examined by UV-vis and in-situ mass spectrometry. This study demonstrates that design nanostructure of PdCu is an efficient approach to facilitate the nitrate reduction process and control the selectivity of N2/NH3.

Enhanced CO2 Adsorption Capability for Highly Selective Electroreduction of CO2 to Formate

Electrochemical reduction of CO2 (CO2RR) has been regarded as a promising approach to reduce CO2 emission and produce value-added fuels simultaneously. However, the low reaction kinetics, high overpotential for the target products, and the competitive hydrogen evolution reaction significantly limit the performance for CO2RR. Thus, it is desirable to design highly active and selective electrocatalysts to advance the electrocatalytic performance. Herein, we prepared bismuth subcarbonate nanoflowers (BOC NFs) as a highly active and selective electrocatalyst for CO2RR to formate formation. The increased formate selectivity of over 90 % is achieved in a wide potential range with good stability and high energy efficiency. The in situ DRIFTS measurement reveals the strong CO2 adsorption capability of BOC NFs that ensures the good accessibility of CO2 during CO2RR. Also, the abundant active sites and fast charge transfer ability of BOC NFs jointly contribute to the improved catalytic performance to formate formation. The density functional theory calculation further confirms the increased adsorption energy of CO2 and intermediate that enhances the performance for CO2RR to formate on BOC NFs. Overall, this electrocatalyst holds a promising future as a candidate for highly selective and effective CO2RR to formate.

The Impact of Nickel Content on Structure and Electrochemical CO2 Reduction Performance of Nickel-Nitrogen-Carbon Catalysts Driven By Zeolitic Imidazolate Frameworks As a Platform

The electrochemical conversion of CO2 to chemicals and fuels is a promising strategy to overcome the increase of CO2 concentration in the atmosphere driven by the extensive dependence on fossil fuels as a main global energy source. A significant shortcoming of this technology is the ability to design new active and selective catalysts for CO2reduction (CO2R) reaction. Atomically dispersed metal-nitrogen doped carbon (M-N-C) materials has attracted extensive attention as highly selective and active electrocatalysts for CO2R due to their exceptional geometric structures and electronic properties compared to other materials. M-N-C electrocatalysts are being synthesized by simple chemical methods through pyrolyzing a mixture of metal salt, nitrogen and carbon containing precursors. Among different precursors, metal organic frameworks (MOFs) are being widely used as a platform for driving M-N-C catalysts owing to their well-defined structures that can assist in forming and isolating the atomically dispersed metal sites doped in N-C skeleton. While several M-N-C (where M=Fe, Co, Mn, Ni) catalysts were utilized for CO2R, atomically dispersed Ni-Nx sites were found to be very selective for the CO2R towards CO. However, the influence of the metal concentration impregnated into the prepared structure on the overall performance of M-N-C catalysts in CO2R is still under investigation.Herein, we’ve selected zeolitic imidazolate frameworks (ZIF-8) — a subclass of MOFs — as a platform for synthesizing Ni-N-C electrocatalyst. A systematic study has been performed to investigate the role of Ni concentration integrated into the structure of ZIF-8 during the synthesis on the structure, properties and overall CO2R activity and selectivity of the prepared Ni-N-C catalyst. A series of four Ni concentrations has been investigated in CO2electroreduction system, our findings exhibit that higher Ni impregnation concentration has resulted in forming metallic Ni nanoparticles which are favouring the competing hydrogen evolution reaction (HER), while low Ni content has assisted on the formation of atomically dispersed and isolated Ni active sites which are very selective towards CO in CO2R ~99% Faradaic efficiency at a potential of -0.68 V vs the reversible hydrogen electrode. Through this study, we show how the optimization of the Ni content in the prepared Ni-N-C catalysts has a significant impact on their performance as CO2R electrocatalysts.

Graphene Oxide Functionalized with Silver Nanoparticles and ZnO Synergic Nanocomposite as an Efficient Electrochemical Sensor for Diclofenac Sodium

The development of a highly sensitive and selective electrocatalyst for the detection of diclofenac sodium (D.S.) has remained a great challenge. In this work, graphene oxide functionalized with silver nanoparticles and zinc oxide (Ag–ZnO–GO) electrocatalyst was developed and investigated for the detection of D.S. The Ag–ZnO–GO/glassy carbon electrode exhibits high sensitivity and fast response within 3[Formula: see text]s owing to the efficient oxidation of D.S. at a very low potential at 0.25[Formula: see text]V. Moreover, the electrode shows a low detection limit of 0.02[Formula: see text][Formula: see text]M ([Formula: see text]) and long-term stability. To explore the synergic effects, the measurements of D.S. using GO, ZnO and ZnO–GO modified electrodes were also performed. The results demonstrate that the Ag–ZnO–GO nanocomposite electrode exhibits enhanced sensitivity and selectivity compared to the other electrodes. In addition, the electrode reveals excellent results for D.S. detection in the real samples as well. The enhanced performance of the proposed electrode is attributed to the improved electron transfer ability and synergic effects of the plasmonic Ag NPs and ZnO–GO structure. It is expected that Ag–ZnO–GO composite is a promising candidate for the construction of cost-effective electrochemical biosensors for medical and industrial applications.

Synergistic Multisites Fe2Mo6S8 Electrocatalysts for Ambient Nitrogen Conversion to Ammonia.

Electrochemical hydrogenation of N2 under ambient conditions is attractive for sustainable and distributable NH3 production but is limited by the lack of selective electrocatalysts. Herein, we describe active site motifs based on the Chevrel phase chalcogenide Fe2Mo6S8 that exhibit intrinsic activities for converting N2 to NH3 in aqueous electrolytes. Despite having a very low specific surface area of ∼2 m2/g, this catalyst exhibited a Faradaic efficiency of 12.5% and an average rate of 70 μg h-1 mgcat-1 for NH3 production at -0.20 V vs RHE. Such activities were attributed to the unique composition and structure of Fe2Mo6S8 that provide synergistic multisites for activating and associating key reaction intermediates. Specifically, Fe/Mo sites assist adsorption and activation of N2, whereas S sites stabilize hydrogen intermediate Had* for N2 hydrogenation. Fe in Fe2Mo6S8 enhances binding of S with Had* and thus inhibits the competing hydrogen evolution reaction. The spatial geometry of Fe, Mo, and S sites in Fe2Mo6S8 promotes conversion of N2-Had* association intermediates, reaching a turnover frequency of ∼0.23 s-1 for NH3 production.

Electrocatalytic activity and volatile product selectivity for nitrate reduction at tin-modified Pt(100), Pd(100) and Pd–Pt(100) single crystal electrodes in acidic media

We prepared Sn-modified Pt(100), Pd(100) and Pd–Pt(100) single crystal electrodes and investigated the nitrate reduction reaction (NO3RR) activity and the product selectivity for them using online electrochemical mass spectroscopy (OLEMS), also known as differential electrochemical mass spectroscopy (DEMS). OLEMS measurements allowed us to quantify volatile products of N2, N2O and NO and confirm the production of N2 at Sn/Pd(100) but not at Sn/Pt(100). Pd-doping to Pt(100) with a 3 atomic % increased the product selectivity for the NO3RR to N2. These results indicate that the presence of Pd in the (100) surface is the key to produce N2, which seems to be related to the hydrogen adsorption energy to the metal surface. The suppression of hydrogenation of intermediate species at the electrode surface could lead to the production of N2. This work will guide us to understand N2 production mechanism for the NO3RR and develop highly selective electrocatalysts for denitrification.

A Metal-Organic Framework derived Cux Oy Cz Catalyst for Electrochemical CO2 Reduction and Impact of Local pH Change.

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 Cu x O y C z 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−/H2O activity ratio due to the locally generated OH− ions at increasing current densities was determined irrespective of the PTFE amount.

Efficient Nitrate-to-Ammonia Electroreduction at Cobalt Phosphide Nanoshuttles.

The nitrate electroreduction reaction (NO3--ERR) is an efficient and green approach for nitrate remediation, which requires a highly active and selective electrocatalyst. In this work, porous and amorphous cobalt phosphide nanoshuttles (CoP PANSs) are successfully synthesized by using Mg2+ ion-doped calcium carbonate nanoshuttles (Mg-CaCO3 NSs) as the initial reaction precursor via precipitation transformation and a high-temperature phosphidation strategy. Various physical characterizations show that CoP PANSs have porous architecture, amorphous crystal structure, and big surface area. Electrochemical measurements reveal for the first time that CoP PANSs have outstanding electroactivity for NO3--ERR in a neutral electrolyte. At an applied potential of -0.5 V vs reversible hydrogen electrode, CoP PANSs can achieve a high Faraday efficiency (94.24 ± 2.8%) and high yield rate (19.28 ± 0.53 mg h-1 mgcat-1) for ammonia production, which exceeds most reported values at various electrocatalysts for NO3--ERR. Thus, the present result indicates that cobalt phosphide nanomaterials have promising application for NO3--ERR.

Operando mechanistic studies of selective oxidation of glycerol to dihydroxyacetone over amorphous cobalt oxide

In this work, cobalt oxide (CoOx) has been demonstrated as an efficient and selective electrocatalyst for producing value-added dihydroxyacetone (DHA) from industrial by-product glycerol. Under optimized conditions, DHA with high selectivity up to 45% and a high production rate of 9.6 μmol h−1 cm−2 is obtained at high current density over 3 mA cm−2 without the occurrence of the oxygen evolution reaction. Operando Raman spectroscopy features the potential-induced structural transformation between CoOx and oxyhydroxides from which a correlation among applied potential, surface chemistry of electrocatalyst, and product distribution are built. These results point toward the viability of using inexpensive materials for electrochemical biomass upgrading as well as providing opportunities for studying structural evolution and activity origin of catalysts under realistic working conditions that can be widely extended to most electrocatalytic biomass valorization processes.

Electrocatalytic generation of hydrogen peroxide on cobalt nanoparticles embedded in nitrogen-doped carbon

Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide (H2O2). The current challenges concern seeking low-cost, highly active, and selective electrocatalysts. Cobalt-nitrogen-doped carbon containing catalytically active cobalt-nitrogen (Co-Nx) sites is an emerging class of materials that can promote the electrochemical generation of H2O2. Here, we report a straightforward method for the preparation of cobalt-nitrogen-doped carbon composed of a number of Co-Nx moieties using low-energy dry-state ball milling, followed by controlled pyrolysis. This scalable method uses inexpensive materials containing cobalt acetate, 2-methylimidazole, and Ketjenblack EC-600JD as the metal, nitrogen, and carbon precursors, respectively. Electrochemical measurements in an acidic medium show the present material exhibits a significant increase in the oxygen reduction reaction current density, accompanied by shifting the onset potential into the positive direction. The current catalyst has also demonstrated an approximate 90 % selectivity towards H2O2 across a wide range of potential. The H2O2 production rate, as measured by H2O2 bulk electrolysis, has reached 100 mmol gcat.−1 h−1 with high H2O2 faradaic efficiency close to 85% (for 2 h at 0.3 V vs. RHE). Lastly, the catalyst durability has been tested (for 6 h at 0.3 V vs. RHE). The catalyst has shown relatively consistent performance, while the overall faradic efficiency reaches approximate 85% throughout the test cycle indicating the promising catalyst durability for practical applications. The formed Co-Nx moieties, along with other parameters, including the acidic environment and the applied potential, likely are the primary reasons for such high activity and selectivity to H2O2 production.

Surface regulated Ni nanoparticles on N-doped mesoporous carbon as an efficient electrocatalyst for CO2 reduction

Low cost, highly selective and efficient electrocatalysts for CO2 reduction reaction (CO2RR) is crucial for lowering the global carbon footprint and mitigating energy shortages. Here, we first report a highly selective and efficient electrocatalyst for CO2RR to CO using a surface-regulated Ni nanoparticles supported on N-doped CMK-3 (N,O-Ni/CMK3). Compared with most Ni metal catalysts previously reported with severe competitive hydrogen evolution during the CO2RR, the N,O-Ni/CMK3 catalyst presents a superior CO faradaic efficiency of about 97%, a high CO partial current density (13.01 mA cm−1) and turnover frequency (4.25 s−1). The comprehensive characterization provides evidence that the N,O co-regulated Ni acts as the active center. Taking advantage of the N, O co-regulated chemical environment, N,O-Ni/CMK3 also displays a decent stability at negative potentials. Our work paves a novel approach for developing transition metal catalysts for CO2RR with enhanced activity and selectivity via regulating surface chemical environment.