Viologen-Cucurbit[7]uril Based Polyrotaxanated Covalent Organic Networks: A Metal Free Electrocatalyst for Oxygen Evolution Reaction.

Viologen-based covalent organic networks represent a burgeoning class of materials distinguished by their captivating properties. Here, supramolecular chemistry is harnessed to fabricate polyrotaxanated ionic covalent organic polymers (iCOP) through a Schiff-base condensation reaction under solvothermal conditions. The reaction between 1,1'-bis(4-aminophenyl)-[4,4'-bipyridine]-1,1'-diium dichloride (DPV-NH2) and 1,3,5-triformylphloroglucinol (TPG) in various solvents yields an iCOP-1 and iCOP-2. Likewise, employing cucurbit[7]uril (CB[7]) in the reaction yielded polyrotaxanated iCOPs, denoted as iCOP-CB[7]-1 and iCOP-CB[7]-2. All four iCOPs exhibit exceptional stability under the acidic and basic conditions. iCOP-CB[7]-2 displays outstanding electrocatalytic Oxygen Evolution Reaction (OER) performance, demanding an overpotential of 296 and 332 mV at 10 and 20 mA cm-2, respectively. Moreover, the CB[7] integrated iCOP-2 exhibits a long-term stable nature for 30 h in 1 m KOH environment. Further, intrinsic activity studies like TOF show a 4.2-fold increase in generation of oxygen (O2) molecules than the bare iCOP-2. Also, it is found that iCOP-CB[7]-2 exhibits a high specific (19.48 mA cm-2) and mass activity (76.74 mA mg-1) at 1.59 V versus RHE. Operando-EIS study evident that iCOP-CB[7]-2 commences OER at a relatively low applied potential of 1.5 V versus RHE. These findings pave the way for a novel approach to synthesizing various mechanically interlocked molecules through straightforward solvothermal conditions.

Efficiency Conceptualization Model: A Theoretical Method for Predicting the Turnover of Catalysts.

In recent times, the theoretical prediction of catalytic efficiency is of utmost urgency. With the advent of density functional theory (DFT), reliable computations can delineate a quantitative aspect of the study. To this state-of-the-art approach, valuable incorporation would be a tool that can acknowledge the efficiency of a catalyst. In the current work, we developed the efficiency conceptualization model (ECM) that utilizes the quantum mechanical tool to achieve efficiency in terms of turnover frequency (TOF). Twenty-six experimentally designed transition metal (TM) water oxidation catalysts were chosen under similar experimental conditions of temperature, pressure, and pH to execute the same. The computations conclude that the Fe-based [Fe(OTf)2(Me2Pytacn)] (MWOC-17) is a highly active catalyst and, therefore, can endure for more time in the catalytic cycle. Our results conclude that the Ir-based catalysts [Cp*Ir(κ2-N,O)X] with MWOC-23: X=Cl; and MWOC-24: X=NO3 report the highest computed turnover numbers (TONs), τ c o m p u t e d T O N 0 ${\tau _{computed\;TON}^0 }$ of 406 and 490 against the highest experimental TONs, τ e x p e r i m e n t a l T O N ${\tau _{experimental\;TON} }$ of 1200 and 2000 respectively, whereas the Co-based [Co(12-TMC)]2+ (MWOC-19) has the lowest TONs ( τ c o m p u t e d T O N 0 ${\tau _{computed\;TON}^0 }$ =19, τexperimental TON=16) among the chosen catalysts and thereby successful in corroborating the previous experimental results.

Defects engineering on CrOOH by Ni doping for boosting electrochemical oxygen evolution reaction.

The design and construction of active centres are key to exploring advanced electrocatalysts for oxygen evolution reaction (OER). In this work, we demonstrate thein situconstruction of point defects on CrOOH by Ni doping (Ni-CrOOH/NF). Compared with pure CrOOH/NF, Ni-CrOOH/NF showed enhanced OER activity. The effect of the amount of Ni introduced on the OER performance was investigated. Ni0.2-CrOOH/NF, the best introduction of Ni, uses a low overpotential of 253 mV to achieve a current density of 10 mA cm-2with a high turnover frequency of 0.27 s-1in 1.0 M NaOH. In addition, the electrocatalytic performance of Ni0.2-CrOOH/NF showed little deterioration after 1000-cycle cyclic voltammetry scanning. In the potentiostatic test, activity was stable for at least 20 h.

The Relationship between Sleeping Position and Sleep Quality: A Flexible Sensor-Based Study.

The use of flexible wearable sensors to monitor the impact of sleeping position and turning frequency on sleep and to study sleep patterns can help bedridden patients heal and recover. The flexible wearable sleeping-position monitoring device was designed and developed using a flexible angle sensor and a six-axis motion sensor to measure the dynamic changes in body posture during sleep. Based on the changes in the output parameters of the flexible angle sensor and the six-axis motion sensor, we determined the change in the subject's lying position, verifying and analyzing the relationship between lying position preference, turning frequency, and sleep quality in healthy subjects. The sleeping-position monitoring device was worn by 13 subjects (7 males and 6 females) without sleep disorders before the sleep experiment. They performed more than 50 sleeping-position changes to ensure the accuracy of the monitoring device. Subjects slept in their beds for 8 h per night for 15 nights. During that time, they wore the sleeping-position monitoring device and a wristband sleep-monitoring bracelet on their left hand, and gathered the subjective sleep data using questionnaires. The results show that the most critical influencing factors are sleeping-position preference and frequency of turning. Data analysis reveals that subjects with a preference for right-sided lying and a lower frequency of turning had better sleep quality.

Covalent Organic Framework (COF) Derived Ni-N-C Catalysts for Electrochemical CO2 Reduction: Unraveling Fundamental Kinetic and Structural Parameters of the Active Sites.

Electrochemical CO2 reduction is a potential approach to convert CO2 into valuable chemicals using electricity as feedstock. Abundant and affordable catalyst materials are needed to upscale this process in a sustainable manner. Nickel-nitrogen-doped carbon (Ni-N-C) is an efficient catalyst for CO2 reduction to CO, and the single-site Ni-Nx motif is believed to be the active site. However, critical metrics for its catalytic activity, such as active site density and intrinsic turnover frequency, so far lack systematic discussion. In this work, we prepared a set of covalent organic framework (COF)-derived Ni-N-C catalysts, for which the Ni-Nx content could be adjusted by the pyrolysis temperature. The combination of high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure evidenced the presence of Ni single-sites, and quantitative X-ray photoemission addressed the relation between active site density and turnover frequency.

Evaluation of the Specific Activity of M-N-Cs and the Intrinsic Activity of Tetrapyrrolic FeN4 Sites for the Oxygen Reduction Reaction.

M-N-C electrocatalysts are considered pivotal to replace expensive precious group metal-based materials in electrocatalytic conversions. However, their development is hampered by the limited availability of methods for the evaluation of the intrinsic activity of different active sites, like pyrrolic FeN4 sites within Fe-N-Cs. Currently, new synthetic procedures based on active-site imprinting followed by an ion exchange reaction, e.g. Zn-to-Fe, are producing single-site M-N-Cs with outstanding activity. Based on the same replacement principle, we employed a conservative iron extraction to partially remove the Fe ions from the N4 cavities in Fe-N-Cs. Having catalysts with the same morphological properties and Fe ligation that differ solely in Fe content allows for the facile determination of the decrease in density of active sites and their turn-over frequency. In this way, insight into the specific activity of M-N-Cs is obtained and for single-site catalysts the intrinsic activity of the site is accessible. This new approach surpasses limitations of methods that rely on probe molecules and, together with those techniques, offers a novel tool to unfold the complexity of Fe-N-C catalyst and M-N-Cs in general.

In situsynthesis of Fe-doped CrOOH nanosheets for efficient electrocatalytic water oxidation.

The oxygen evolution reaction (OER) is a process in electrochemical water splitting with sluggish kinetics that needs efficient non-noble-metal electrocatalysts. There have been few studies of CrOOH electrocatalysts for water oxidation due to their low performance. Herein,in situsynthesized Fe-doped CrOOH nanosheets on Ni foam (Fe-CrOOH/NF) were designed as electrocatalysts and performance in the OER was obviously improved. The effect of the amount of Fe doping was also investigated. Experiments revealed that the best performance of Fe-CrOOH/NF requires low overpotentials of 259 mV to reach 20 mA cm-2together with a turnover frequency of 0.245 s-1in 1.0 M KOH, which may suggest a new direction for the development of Fe-doped OER electrocatalysts.

Innovative green/non-toxic Bi2S3@g-C3N4 nanosheets for dark antimicrobial activity and photocatalytic depollution: Turnover assessment.

Herein, green and non-toxic bismuth sulphide@graphitic carbon nitride (Bi2S3@g-C3N4) nanosheets (NCs) were firstly synthesized by ultrasonicated-assisted method and characterized with different tool. Bi2S3@g-C3N4 NCs antimicrobial activity tested against three types of microbes. As well the heterostructured Bi2S3@g-C3N4 NCs was investigated for removing dye and hexavalent chromium under visible light and showed high efficiency of photocatalytic oxidation/reduction higher than g-C3N4 alone, attributing to lower recombination photogenerated electron-hole pairs. Bi2S3@g-C3N4 NCs showed high antimicrobial efficiencies against Staphylococcus aureus (S. aureus) as a Gram positive bacterium, Escherichia coli (E. Coli)as a Gram negative bacterium and Candida albicans (C. albicans) and that the disinfection rates are 99.97%, 99.98% and 99.92%, respectively. The core mechanism is that the bacterial membrane could be destroyed by reactive oxygen species. The Bi2S3@g-C3N4 NCs is promising for environmental disinfection including water and public facilities disinfection and solar photocatalytic depollution. Turnover number (TON) and Turnover frequency (TOF) are used as concise assessment indicator for photocatalytic efficiency.

The Significance of Properly Reporting Turnover Frequency in Electrocatalysis Research.

For decades, turnover frequency (TOF) has served as an accurate descriptor of the intrinsic activity of a catalyst, including those in electrocatalytic reactions involving both fuel generation and fuel consumption. Unfortunately, in most of the recent reports in this area, TOF is often not properly reported or not reported at all, in contrast to the overpotentials at a benchmarking current density. The current density is significant in determining the apparent activity, but it is affected by catalyst-centric parasitic reactions, electrolyte-centric competing reactions, and capacitance. Luckily, a properly calculated TOF can precisely give the intrinsic activity free from these phenomena in electrocatalysis. In this Viewpoint we ask: 1) What makes the commonly used activity markers unsuitable for intrinsic activity determination? 2) How can TOF reflect the intrinsic activity? 3) Why is TOF still underused in electrocatalysis? 4) What methods are used in TOF determination? and 5) What is essential in the more accurate calculation of TOF? Finally, the significance of normalizing TOF by Faradaic efficiency (FE) is stressed and we give our views on the development of universal analytical tools to determine the exact number of active sites and real surface area for all kinds of materials.

Oxygen Evolution Electrocatalysis of a Single MOF-Derived Composite Nanoparticle on the Tip of a Nanoelectrode.

Determination of the intrinsic electrocatalytic activity of nanomaterials by means of macroelectrode techniques is compromised by ensemble and film effects. Here, a unique "particle on a stick" approach is used to grow a single metal-organic framework (MOF; ZIF-67) nanoparticle on a nanoelectrode surface which is pyrolyzed to generate a cobalt/nitrogen-doped carbon (CoN/C) composite nanoparticle that exhibits very high catalytic activity towards the oxygen evolution reaction (OER) with a current density of up to 230 mA cm-2 at 1.77 V (vs. RHE), and a high turnover frequency (TOF) of 29.7 s-1 at 540 mV overpotential. Identical location transmission electron microscopy (IL-TEM) analysis substantiates the "self-sacrificial" template nature of the MOF, while post-electrocatalysis studies reveal agglomeration of Co centers within the CoN/C composite during the OER. "Single-entity" electrochemical analysis allows for deriving the intrinsic electrocatalytic activity and furnishes insight into the transient behavior of the electrocatalyst under reaction conditions.

Tuning the Activity and Stability of CoCr-LDH by Forming a Heterostructure on Surface-Oxidized Nickel Foam for Enhanced Water-Splitting Performance.

The development of low-cost, efficient catalysts for electrocatalytic water splitting to generate green hydrogen is a hot topic among researchers. Herein, we have developed a highly efficient heterostructure of CoCr-LDH on NiO on nickel foam (NF) for the first time. The preparation strategy follows the simple annealing of a cleaned NF without using any Ni salt precursor, followed by the growth of CoCr-LDH nanosheets over the surface-oxidized NF. The CoCr-LDH/NiO/NF catalyst shows excellent electrocatalytic activity and stability toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in a 1 M KOH solution. For OER, only 253 mV and for HER, only 185 mV overpotentials are required to attain a 50 mA cm-2 current density. Also, the long-term stability of both the OER and HER for 60 h proves its robustness. The turnover frequency value for the OER increased 1.85 times after the heterostructure formation compared to bare CoCr-LDH. The calculated Faradaic efficiency values of 97.4 and 94.75% for the OER and HER revealed the high intrinsic activity of the heterostructure. Moreover, the heterostructure only needs 1.57 V of cell voltage when acting as both the anode and the cathode to achieve a 10 mA cm-2 current density. The long-term stability of 60 h for the total water-splitting process proves its excellent performance. Several systematic pre- and post-experiment characterizations prove its durable nature. These excellent OER and HER activities and stabilities are attributed to the surface-modified electronic structure and thin nanosheet-like surface morphology of the heterostructure. The thin, wide, and modified surface of the catalyst facilitates the diffusion of ions (reactants) and gas molecules (products) at the electrode/electrolyte interface. Furthermore, electron transfer from n-type CoCr-LDH to p-type NiO results in enhanced electronic conductivity. This study demonstates the effective design of a self-supported heterostructure with minimal synthetic steps to generate a bifunctional electrocatalyst for water splitting, contributing to the greater cause of green hydrogen economy.

Ultra-Low-Loaded Platinum Bonded Hexagonal Boron Nitride as Stable Electrocatalyst for Hydrogen Generation.

Chemical stability of hexagonal boron nitride (hBN) ultrathin layers in harsh electrolytes and the availability of nitrogen site in hBN to stabilize metals like Pt are used here to develop a high intrinsic activity hydrogen evolution reaction (HER) catalyst having low loaded Pt (5 weight% or <1 atomic%). A catalyst having a nonzero oxidation state for Pt (with a Pt-N bonding) is shown to be HER active even with low catalyst loadings (0.114 mgcm-2). Electronic modification of the shear exfoliated hBN sheets is achieved by Au nanoparticle-based surface decoration (hBN_Au), and further anchoring with Pt develops a catalyst (hBN_Au_Pt) with high turnover frequency for HER (∼15). The hBN_Au_Pt is shown to be a highly durable catalyst even after the accelerated durability test for 10000 cycles and temperature annealing at 100 °C. Density functional theory based calculations gave insights in to the electronic modifications of hBN with Au and the catalytic activity of the hBN_Au_Pt system, in line with the experimental studies, indicating the demonstration of a new class of catalyst system devoid of issues such as carbon corrosion and Pt leaching.

Ce-Doped TiO2 Fabricated Glassy Carbon Electrode for Efficient Hydrogen Evolution Reaction in Acidic Medium.

The quest for sustainable and clean energy sources has intensified research on the Hydrogen Evolution Reaction (HER) in recent decades. In this study, we have presented a novel Ce-doped TiO2 catalyst synthesized through the sol-gel method, showcasing its potential as a superior electrocatalyst for HER in an acidic medium. Comprehensive characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray (EDX), and Raman spectroscopy confirms the successful formation of the catalyst. Electrocatalytic performance evaluation, including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Tafel analysis, demonstrates that GCE-5wt.%CeTiO2 outperforms bare GCE, as well as Ce and TiO2-based electrodes. Kinetic investigations reveal a Tafel slope of 105 mV dec-1, indicating the Volmer step as the rate-determining step. The onset potential for HER at GCE-5wt.%CeTiO2 is -0.16 V vs. RHE, close to the platinum electrode. Notably, the catalyst exhibits a low overpotential of 401 mV to achieve a current density of 10 mA cm-2 with an impressive 95 % Faradaic efficiency. Furthermore, the catalyst demonstrates outstanding durability, maintaining a negligible increase in overpotential during a 14-hour chronoamperometry test. These results have far-reaching implications for the development of cost-effective and efficient electrocatalysts for hydrogen production.

Enhanced photocatalytic performance of auto-combusted nanoparticles for photocatalytic degradation of azo dye under sunlight illumination and hydrogen fuel production.

In this study, an innovative nanomaterial was synthesized for hydrogen production from methanolysis on sodium borohydride (NaBH4) in order to be a solution for future energy problems. The nanocomposite containing FeCo, which does not contain noble metals, and whose support material is Polyvinylpyrrolidone (PVP), was synthesized by means of a thermal method. TEM, XRD and FTIR characterization methods were used for the analysis of the morphological and chemical structure of the nanocomposite. Nanocomposite particle size was found to be 2.59 nm according to XRD analysis, and 5.45 nm according to TEM analysis for scale of 50 nm. For catalytic properties of nanomaterial in the methanolysis reaction of NaBH4, temperature, catalyst, substrate, and reusability experiments were carried out and kinetic calculations were obtained. Among the activation parameters of FeCo@PVP nanoparticles, turnover frequency, enthalpy, entropy and activation energy were calculated as 3858.9 min-1, 29.39 kJ/mol, -139.7 J/mol.K, and 31.93 kJ/mol, respectively. As a result of the reusability test of the obtained FeCo@PVP nanoparticles catalysts, which was carried out for 4 cycles, the catalytic activity was 77%. Catalytic activity results are given in comparison with the literature. In addition, the photocatalytic activity of FeCo@PVP NPs was evaluated against MB azo dye under solar light irradiation for 75 min and was found to be as 94%.

Approach to Evaluation of Electrocatalytic Water Splitting Parameters, Reflecting Intrinsic Activity: Toward the Right Pathway.

The development of transition metal-based non-precious-metal electrocatalysts for energy storage and conversion systems has received a lot of interest recently. To further this subject in the proper way given the development of electrocatalysts, a fair comparison of their respective performance is necessary. This Review investigates the parameters used for the comparison of electrocatalyst activity. Significant evaluation criteria employed in electrochemical water splitting studies are the overpotential at defined current density usually at 10 mA per geometric surface area, Tafel slope, exchange current density, mass activity, specific activity and turnover frequency (TOF). This Review will discuss how to identify the specific activity and TOF by electrochemical and non-electrochemical methods to represent intrinsic activity as well as the benefits and uncertainties of each technique, ensuring that each method is applied correctly when calculating intrinsic activity metrics.

Recognizing zeolite topologies for Cu2+ localizations with effective activities for selective catalytic reduction of nitrogen oxide.

Cu-loaded zeolites are widely investigated in selective catalytic reduction of nitrogen oxide, but effects of zeolite topologies on formed active species and the changing tendency remain unexplored. In this work, catalytic turnover frequencies (TOF) of Cu loaded ZSM-5, Beta, MOR, and SSZ-13 were first determined. The topology-localized Cu species in these zeolites were analyzed by temperature-programmed reduction of H2. Then Multiple Linear Regression distinguished TOF contributions (kj, s-1·mol-1) of the Cu species. Density functional theory calculated NH3 dehydrogenation energy of the Cu species. As a result, topologies with more node atoms showed bigger kj and lower dehydrogenation energies simultaneously. The best topology in each zeolite was 10-membered ring (ZSM-5), 6-membered ring facing a 12-membered ring (Beta), 8-membered ring (MOR), and cha cage (SSZ-13). Moreover, cha cage-localized Cu2+ exhibited the largest kj and the lowest dehydrogenation energy among all the Cu species. This work reveals topology-catalysis relationships in the zeolite, which benefits zeolite design for enhanced catalytic performances.

Modulating the Asymmetric Atomic Interface of Copper Single Atoms for Efficient CO2 Electroreduction.

Cu single-atom catalysts (Cu SACs) have been considered as promising catalysts for efficient electrocatalytic CO2 reduction reactions (ECRRs). However, the reports on Cu SACs with an asymmetric atomic interface to obtain CO are few. Herein, we rationally designed two Cu SACs with different asymmetric atomic interfaces to explore their catalytic performance. The catalyst of CuN3O/C delivers high ECRR selectivity with an FECO value of above 90% in a wide potential window from -0.5 to -0.9 V vs RHE (in particular, 96% at -0.8 V), while CuCO3/C delivers poor selectivity for CO production with a maximum FECO value of only 20.0% at -0.5 V vs RHE. Besides, CuN3O/C exhibited a large turnover frequency (TOF) up to 2782.6 h-1 at -0.9 V vs RHE, which is much better than the maximum 4.8 h-1 of CuCO3/C. Density functional theory (DFT) results demonstrate that the CuN3O site needs a lower Gibbs free energy than CuCO3 in the rate-determining step of CO desorption, leading to the outstanding performance of CuN3O/C on the process of ECRR-to-CO. This work provides an efficient strategy to improve the selectivity and activity of the ECRR via regulating asymmetric atomic interfaces of SACs by adjusting the coordination atoms.

Regulating the electronic structures of mixed B-site pyrochlore to enhance the turnover frequency in water oxidation.

This paper describes the development of mixed B-site pyrochlore Y2MnRuO7 electrocatalyst for oxygen evolution reaction (OER) in acidic media, a challenge for the development of low-temperature electrolyzer for green hydrogen production. Recently, several theories have been developed to understand the reaction mechanism for OER, though there is an  uncertainty in most of the cases, due to the complex surface structures. Several key factors such as lattice oxygen, defect, electronic structure, oxidation state, hydroxyl group and conductivity were identified and shown to be important to the OER activity. The contribution of each factor to the performance however is often not well understood, limiting their impact in guiding the design of OER electrocatalysts. In this work, we showed mixed B-site pyrochlore Y2MnRuO7 catalyst exhibits 14 times higher turnover frequency (TOF) than RuO2 while maintaining a low overpotential of ~ 300 mV for the entire testing period of 24 h in acidic electrolyte. X-ray photoelectron spectroscopy (XPS) analysis reveals that this B-site mixed pyrochlore Y2MnRuO7 has a higher oxidation state of Ru than those of Y2Ru2O7, which could be crucial for improving OER performance as the broadened and lowered Ru 4d band resulted from the B-site substitution by Mn is beneficial to the OER kinetics.

Highly efficient overall urea electrolysis via single-atomically active centers on layered double hydroxide.

Anodic urea oxidation reaction (UOR) is an intriguing half reaction that can replace oxygen evolution reaction (OER) and work together with hydrogen evolution reaction (HER) toward simultaneous hydrogen fuel generation and urea-rich wastewater purification; however, it remains a challenge to achieve overall urea electrolysis with high efficiency. Herein, we report a multifunctional electrocatalyst termed as Rh/NiV-LDH, through integration of nickel-vanadium layered double hydroxide (LDH) with rhodium single-atom catalyst (SAC), to achieve this goal. The electrocatalyst delivers high HER mass activity of 0.262 A mg-1 and exceptionally high turnover frequency (TOF) of 2.125 s-1 at an overpotential of 100 mV. Moreover, exceptional activity toward urea oxidation is addressed, which requires a potential of 1.33 V to yield 10 mA cm-2, endorsing the potential to surmount the sluggish OER. The splendid catalytic activity is enabled by the synergy of the NiV-LDH support and the atomically dispersed Rh sites (located on the Ni-V hollow sites) as evidenced both experimentally and theoretically. The self-supported Rh/NiV-LDH catalyst serving as the anode and cathode for overall urea electrolysis (1 mol L-1 KOH with 0.33 mol L-1 urea as electrolyte) only requires a small voltage of 1.47 V to deliver 100 mA cm-2 with excellent stability. This work provides important insights into multifunctional SAC design from the perspective of support sites toward overall electrolysis applications.

Efficient Alkaline Water Oxidation with a Regenerable Nickel Pseudo-Complex.

Efficient and robust electrocatalysts are required for the oxygen evolution reaction (OER). Photosystem II-inspired synthetic transition metal complexes have shown promising OER activity in water-poor or mild conditions, yet challenges remain in the improvement of current density and performance stability for practical applications in alkaline electrolytes in contrast to solid-state oxide catalysts. Here, we report that a nickel pseudo-complex (bpy)zNiOxHy (bpy = 2,2'-bipyridine) catalyst, which bridges solid oxide and molecular catalysts, exhibits the highest OER activity among nickel-based catalysts with a turnover frequency of 1.1 s-1 at an overpotential of 0.30 volts, even outperforming iron-incorporated nickel (oxy)hydroxide under an identical nickel mass load. Benefiting from the strong coordination between bpy and nickel, this (bpy)zNiOxHy catalyst exhibits long-term stability in highly alkaline media at 1.0 mA cm-2 for over 200 h and at 20 mA cm-2 for over 60 h. Our findings indicate that dynamically coordinating a small amount of bpy in the catalyst layer efficiently sustains highly active nickel sites for water oxidation, demonstrating a general strategy for improving the activity of transition metal sites with active ligands beyond the incorporation of metal cations to form double-layered hydroxides.