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A novel oxygen reduction reaction (ORR) electrode comprising isolated Co atom decorated vertically aligned graphene nanosheets is designed, which can enable the most energy-efficient, rapid acidic H2O2 production in a flow-cell reactor.

We investigated the CO2 adsorption and electrochemical conversion behavior of triazole-based C3 N5 nanorods as a single matrix for consecutive CO2 capture and conversion. The pore size, basicity, and binding energy were tailored to identify critical factors for consecutive CO2 capture and conversion over carbon nitrides. Temperature-programmed desorption (TPD) analysis of CO2 demonstrates that triazole-based C3 N5 shows higher basicity and stronger CO2 binding energy than g-C3 N4 . Triazole-based C3 N5 nanorods with 6.1 nm mesopore channels exhibit better CO2 adsorption than nanorods with 3.5 and 5.4 nm mesopore channels. C3 N5 nanorods with wider mesopore channels are effective in increasing the current density as an electrocatalyst during the CO2 reduction reaction. Triazole-based C3 N5 nanorods with tailored pore sizes exhibit CO2 adsorption abilities of 5.6-9.1 mmol/g at 0 °C and 30 bar. Their Faraday efficiencies for reducing CO2 to CO are 14-38% at a potential of -0.8 V vs. RHE.

A considerable amount of platinum (Pt) is required to ensure an adequate rate for oxygen reduction reactions (ORR) in fuel cells and metal-air batteries. Thus, the implementation of atomic Pt catalysts holds promise for minimizing the contents of Pt. In this contribution, atomic Pt sites with nitrogen (N) and phosphorus (P) co-coordination on carbon matrix (PtNPC) are conceptually predicted and experimentally developed to alter the d -band center of Pt, thereby promoting the intrinsic ORR activity. The PtNPC with a record-low Pt content (~0.026 wt%) consequently shows a benchmark-comparable activity for ORR with an onset of 1.0 V RHE and half-wave potential of 0.85 V RHE . It also features a high stability in 15,000-cycle tests and a superior turnover frequency of 6.80 s -1 at 0.9 V RHE . Damjanovic kinetics analysis reveals a tuned ORR kinetics of PtNPC from mixed 2/4-electron to predominate 4-electron route. It is discovered that coordinated P species significantly shifts d -band center of Pt atoms, accounting for the exceptional performance of PtNPC.

In this study, we propose a top-down approach for the controlled preparation of undercoordinated Ni-Nx (Ni-hG) and Fe-Nx (Fe-hG) catalysts within a holey graphene framework, for the electrochemical CO2 reduction reaction (CO2RR) to synthesis gas (syngas). Through the heat treatment of commercial-grade nitrogen-doped graphene, we prepared a defective holey graphene, which was then used as a platform to incorporate undercoordinated single atoms via carbon defect restoration, confirmed by a range of characterization techniques. We reveal that these Ni-hG and Fe-hG catalysts can be combined in any proportion to produce a desired syngas ratio (1-10) across a wide potential range (-0.6 to -1.1 V vs RHE), required commercially for the Fischer-Tropsch (F-T) synthesis of liquid fuels and chemicals. These findings are in agreement with our density functional theory calculations, which reveal that CO selectivity increases with a reduction in N coordination with Ni, while unsaturated Fe-Nx sites favor the hydrogen evolution reaction (HER). The potential of these catalysts for scale up is further demonstrated by the unchanged selectivity at elevated temperature and stability in a high-throughput gas diffusion electrolyzer, displaying a high-mass-normalized activity of 275 mA mg-1 at a cell voltage of 2.5 V. Our results provide valuable insights into the implementation of a simple top-down approach for fabricating active undercoordinated single atom catalysts for decarbonized syngas generation.

Hydrogen production through water electrolysis is a promising method to utilize renewable energy in the context of urgent need to phase out fossil fuels. Nickel-molybdenum (NiMo) electrodes are among the best performing non-noble metal-based electrodes for hydrogen evolution reaction in alkaline media (alkaline HER). Albeit exhibiting stable performance in electrolysis at a constant power supply (i.e., constant electrolysis), NiMo electrodes suffer from performance degradation in electrolysis at an intermittent power supply (i.e., intermittent electrolysis), which is emblematic of electrolysis powered directly by renewable energy (such as wind and solar power sources). Here we reveal that NiMo electrodes were oxidized by dissolved oxygen during power interruption, leading to vanishing of metallic Ni active sites and loss of conductivity in MoO

The electrochemical oxygen reduction reaction (ORR) provides a green route for decentralized H2 O2 synthesis, where a structure-selectivity relationship is pivotal for the control of a highly selective and active two-electron pathway. Here, we report the fabrication of a boron and nitrogen co-doped turbostratic carbon catalyst with tunable B-N-C configurations (CNB-ZIL) by the assistance of a zwitterionic liquid (ZIL) for electrochemical hydrogen peroxide production. Combined spectroscopic analysis reveals a fine tailored B-N moiety in CNB-ZIL, where interfacial B-N species in a homogeneous distribution tend to segregate into hexagonal boron nitride domains at higher pyrolysis temperatures. Based on the experimental observations, a correlation between the interfacial B-N moieties and HO2 - selectivity is established. The CNB-ZIL electrocatalysts with optimal interfacial B-N moieties exhibit a high HO2 - selectivity with small overpotentials in alkaline media, giving a HO2 - yield of ≈1787 mmol gcatalyst -1 h-1 at -1.4 V in a flow-cell reactor. ispartof: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION vol:61 issue:37 ispartof: location:Germany status: published

The last decade has witnessed an extensive uptake of clean and sustainable energy sources to meet the surging energy demand while mitigating the increasing levels of greenhouse gas emission and air pollution. Among various energy systems, electrochemical energy storage devices such as batteries and supercapacitors have attracted worldwide attention for use in electric-powered transport, portable electronics, and biomedical devices. Recently, new multifunctional supercapacitors, which combine energy storage capability with load-carrying and other functions, offer a new “two-birds-one-stone” strategy for next-generation energy storage systems to store energy beyond the traditional systems. Multifunctional supercapacitors show great promise in reducing the size and volume of devices, improving the charge storage capacity, and minimising the cost in materials and fabrication while bringing the benefits of additional functions to the systems. This review describes the recent advances in multifunctional supercapacitors in terms of materials design, device configuration, system integration, and applications. The unique features of multifunctional supercapacitors depend strongly on architectural designs and system integration, which allow elimination of certain components to reduce the size and weight, thus improving the overall system performance. The review focuses specifically on multifunctional supercapacitors with novel mechanical, surface/interfacial, thermal, electronic, photodetection and energy harvesting/conversion functions. In addition, challenges and opportunities for further developments in the emerging field of multifunctional supercapacitors are suggested and discussed.

Critical to the feasibility of electrochemical reduction of waste NOx (NOxRR), as a sustainable pathway and to close the NOx cycle for the emerging NH3 economy, is the requirement of inexpensive, scalable and selective catalysts that can generate NH4+ with high yield, as indicated by our economic modelling. To this end, we carry out density functional theory (DFT) calculations to investigate the possible contribution of oxygen vacancy (OV) defects in NOxRR catalysis, discovering that an increase in defect density within CuO is leading to a decrease in adsorption energy for NO3− reactants. Using these findings as design guidelines, we develop defective CuO nanomaterials using flame spray pyrolysis (FSP) and mild plasma treatment, that can attain a NH4+ yield of 520 μmol cm−2 h−1 at a cell voltage of 2.2 V within a flow electrolyser with good stability over 10 h of operation. Through our mechanistic investigation, we establish the beneficial role of oxygen vacancy defects (with one free electron) in CuO for NOxRR and we reveal a direct correlation of oxygen vacancy density with the NH4+ yield, arising from improved NO3− adsorption, as evidenced from our theoretical calculations. Our findings on defect engineering to improve NH4+ yield and its economic feasibility display the potential of NOxRR as an alternative pathway to generate green NH3, which can also serve as an energy vector for the emerging hydrogen economy and close the NOx cycle.

Bandgap engineered ferroelectrics exhibit encouraging multi-energy catalytic performance by coupling the piezoelectricity and photoexcitation, which shows immense potential for environmental remediation and fuel production. However, it is challenging to prepare nano single-crystalline ferroelectric piezo-photoelectric with strong visible light absorption ability. Here, Ni mediated NBT-BT(NBT-BNT) single-crystalline nanocubes around 100 nm with considerable visible light absorption were synthesized by a high-temperature hydrothermal method. The mechanism of Ni2+ on the formation of NBT-BT nanocubes was proposed. The catalytic efficiency of NBT-BNT nanocubes is enhanced by decorating carbon quantum dots (CQDs). The RhB can be degraded within 8 min and the hydrogen production rate reaches up to ∼350 μmol g-1h-1 under visible light-ultrasonic condition. Moreover, under the simulated sunlight-ultrasound condition, RhB can be degraded within merely 3 min and a high H2 production rate of ∼747 μmol g-1h-1 is achieved. This work presents a paradigm for preparing ferroelectric single-crystalline nanocatalysts for multi-energy catalytic application.

Engineering the metal-carbon heterointerface has become an increasingly important route toward achieving cost-effective and high-performing electrocatalysts. The specific properties of graphene edge sites, such as the high available density of states and extended unpaired π-bonding, make it a promising candidate to tune the electronic properties of metal catalysts. However, to date, understanding and leveraging graphene edge-metal catalysts for improved electrocatalytic performance remains largely elusive. Herein, edge-rich vertical graphene (er-VG) was synthesized and used as a catalyst support for Ni-Fe hydroxides for the oxygen evolution reaction (OER). The hybrid Ni-Fe/er-VG catalyst exhibits excellent OER performance with a mass current of 4051 A g-1 (at overpotential η = 300 mV) and turnover frequency (TOF) of 4.8 s-1 (η = 400 mV), outperforming Ni-Fe deposited on pristine VG and other metal foam supports. Angle-dependent X-ray absorption spectroscopy shows that the edge-rich VG support can preferentially template Fe-O units with a specific valence orbital alignment interacting with the unoccupied density of states on the graphene edges. This graphene edge-metal interaction was shown to facilitate the formation of undersaturated and strained Fe-sites with high valence states, while promoting the formation of redox-activated Ni species, thus improving OER performance. These findings demonstrate rational design of the graphene edge-metal interface in electrocatalysts which can be used for various energy conversion and chemical synthesis reactions.

Hydrogen peroxide produced by electrochemical oxygen reduction reaction provides a potentially cost effective and energy efficient alternative to the industrial anthraquinone process. In this study, we demonstrate that by modulating the oxygen functional groups near the atomically dispersed cobalt sites with proper electrochemical/chemical treatments, a highly active and selective oxygen reduction process for hydrogen peroxide production can be obtained in acidic electrolyte, showing a negligible amount of onset overpotential and nearly 100% selectivity within a wide range of applied potentials. Combined spectroscopic results reveal that the exceptionally enhanced performance of hydrogen peroxide generation originates from the presence of epoxy groups near the Co–N4 centers, which has resulted in the modification of the electronic structure of the cobalt atoms. Computational modeling demonstrates these electronically modified cobalt atoms will enhance the hydrogen peroxide productivity during oxygen reduction reaction in acid, providing insights into the design of electroactive materials for effective peroxide production. The production of hydrogen peroxide by electrochemical oxygen reduction is an attractive alternative to the industrial process, but catalysts should be optimized. Here, the authors enhance hydrogen peroxide production in acidic media with epoxy groups near cobalt centers on carbon nanotubes.

The shuttling of polysulfides (PS) is a major technical issue for lithium–sulfur batteries (LSB). Coating the LSB separator is an effective and simple way to mitigate the PS shuttle. However, these...

Controllable concomitant production of CO and H2 (syngas) during electrochemical CO2 reduction reactions (CO2RR) is expected to improve the commercial feasibility of the technology to mitigate CO2 emissions as the generated syngas can be converted into useful chemicals using the commercial Fischer-Tropsch (FT) process. Herein, we demonstrate the ability of a Co single-atom-decorated N-doped graphitic carbon shell-encapsulated cobalt nanoparticle electrocatalyst (referred as Co@CoNC-900) to controllably produce syngas at low overpotentials during CO2RR. Through the engineering and modulation of dual active sites for CO2RR (modified carbon shell with encapsulated Co) and hydrogen evolution reaction (Co-N4 moieties) within Co@CoNC by varying the annealing temperature, we are able to tune the H2: CO ratio from 1: 2 to 1: 1 to 3: 2 over a wide range of applied potentials (-0.5 V to -0.8 V versus reversible hydrogen electrode, RHE). This versatile control of H2: CO ratio in CO2RR reaction brings up significant opportunity of using CO2 and H2O and renewable energy for producing a range of chemicals.

A novel, simple and controllable approach to designing NiO/Ni heterostructures supported on carbon for the hydrogen evolution reaction (HER) was utilized. By selectively oxidizing the Ni deposits, to differing degrees, the benefits of the NiO/Ni heterostructures were elucidated with the extent of Ni oxidation being a key factor in dictating performance.

Zinc–air batteries are regarded as promising candidates for next-generation clean and sustainable energy storage devices, due to their low-cost, safety, eco-friendliness, and high specific energy density. In zinc–air batteries, the air catalysts accelerate the sluggish oxygen electrocatalysis and largely govern the overall battery performance. Among the air catalysts, carbon-based materials have attract great attention, owing to their high conductivity, chemical robustness, porous structure, and tunable composition. Herein, this review presents the recent progress in bifunctional heteroatom-doped carbon catalysts for zinc–air batteries, especially for rechargeable and flexible batteries. The review will start with a brief introduction of the development, advantages, and types of zinc–air batteries. Then, the application of bifunctional heteroatom-doped carbon catalysts for aqueous and solid-state/flexible zinc–air batteries will be summarized. In the review, an emphasis is given for the investigations on reaction mechanisms, along with corresponding discussions on the role of non-metal and metal dopants. Theoretical predictions will also be discussed to guide the design and fabrication of future bifunctional carbon-based catalysts. Finally, a general perspective on the challenges and opportunities for the future innovation of heteroatom-doped carbon-based catalysts for zinc–air batteries is presented.

The structural and electronic properties of MnO2 based electrocatalysts are key factors determining their electrochemical performance. To date, it is still challenging to synergistically tune the crystal structure, morphology, and electronic band (i.e., band gap and band alignments) of MnO2 through facile synthesis approaches. This study has reported a one-step hydrothermal method to synthesize a prototypical MnO2 electrocatalyst with optimized structural and electrochemical properties. By simply adjusting the hydrothermal time, the phase transition from polymorphic d to a can be induced in MnO2. The obtained nanowires on nanosheets structure grown in-situ on nickel foam provides a large surface area, great accessible active sites, and good mass/charge transfer efficiency. Further investigation through first-principles calculations reveals that compared to d-MnO2, the a-MnO2 polymorph with rich oxygen vacancies has better band-alignment tunability, which is also beneficial for improving the electrochemical performance. The a phase MnO2 exhibits superior catalytic performance for both OER and HER (OER overpotential of 0.45 V at 50 mA cm-2 and HER overpotential of 0.14 V at 50 mA cm-2). The developed synthesis method can be extended to catalyst designs that require precise control of phase and morphology evolution in a wide range of applications.

Precise force measurement is critical to probing biological events and physics processes, spanning from molecular motor’s motion to the Casimir effect1 and the detection of gravitational wave2. Yet, despite extensive technology developments, the 3D nanoscale measurement of weak forces in aqueous solutions poses a significant challenge. Techniques that rely on the optically trapped nanoprobe are beset with difficulties, including low light scattering for force measuring and high localization error from their Brownian motion. Here, we report the measurement of the long-distance electrodynamic force on single nanocrystals suspended in aqueous solution with only 11 net charges. To achieve this, we develop an upconversion photonic force microscope that encompasses a diffraction-limited tracking-based force sensing theory and the advance of lanthanide ion resonance force probe3,4. The tracking method is based on neural network empowered super-resolution localization, where the position of force probe is extracted from the optical astigmatism modified point spread functon(PSF), enabling the measurement of trap stiffness for nanoparticles through equipartition theorem with a force sensitivity down to 592.9 attoNewtons (aN), that is, 5 times lower than the reported best sensitivity value5. We further demonstrate that the technology can measure a single nanocrystal's electrophoresis force and zeta potential, experimentally verifying Loeb's empirical relationship. This work offers new opportunities for detecting single-charge dynamics over long-distance and sub-cellular single molecular level biomechanical force.

Electrolytic hydrogen evolution reaction (HER) that can be performed efficiently in neutral conditions enables the direct splitting of seawater. However, the sluggish water dissociation kinetics in neutral media severely limits the practical deployment of this technology. Herein, we present a simple strategy to rationally design oxophilic and nucleophilic moieties through the in situ reconstruction of a free-standing bimetallic cobalt-iron phosphate electrode. Through an electrochemical reduction step, the electrode surface undergoes self-reconstruction to generate a thin (oxy)hydroxide layer, enabling a significantly improved HER activity in both buffered electrolyte and natural seawater. Our mechanistic investigations reveal the essential role of oxophilic (oxy)hydroxide species in improving the HER activity of nucleophilic bimetallic phosphate sites. In a buffer electrolyte (pH = 7), the resultant electrocatalyst only requires overpotentials of 97 and 198 mV to deliver a current density of 10 and 100 mA cm-2, respectively, which outperforms that of the Pt benchmark. The in situ reconstruction strategy of active sites within such electrodes brings significant opportunity in developing active electrocatalysts that are capable of direct seawater splitting.

We investigated the CO

Electrochemical generation of hydrogen peroxide (H2 O2 ) is an attractive alternative to the energy-intensive anthraquinone oxidation process. Metal-free carbon-based materials such as graphene show great promise as efficient electrocatalysts in alkaline media. In particular, the graphene edges possess superior electrochemical properties than the basal plane. However, identification and enhancement of the catalytically active sites at the edges remain challenging. Furthermore, control of surface wettability to enhance gas diffusion and promote the performance in bulk electrolysis is largely unexplored. Here, a metal-free edge-rich vertical graphene catalyst is synthesized and exhibits a superior performance for H2 O2 production, with a high onset potential (0.8 V versus reversible hydrogen electrode (RHE) at 0.1 mA cm-2 ) and 100% Faradaic efficiency at various potentials. By tailoring the oxygen-containing functional groups using various techniques of electrochemical oxidation, thermal annealing and oxygen plasma post-treatment, the edge-bound in-plane ether-type (COC) groups are revealed to account for the superior catalytic performance. To manipulate the surface wettability, a simple vacuum-based method is developed to effectively induce material hydrophobicity by accelerating hydrocarbon adsorption. The increased hydrophobicity greatly enhances gas transfer without compromising the Faradaic efficiency, enabling a H2 O2 productivity of 1767 mmol gcatalyst-1 h-1 at 0.4 V versus RHE.

In this study, we propose a top-down approach for the controlled preparation of undercoordinated Ni-N

Single-atom catalysts (SACs) have been at the frontier of research field in catalysis owing to the maximized atomic utilization, unique structures and properties. The atomically dispersed and catalytically active metal atoms are necessarily anchored by surrounding atoms. As such, the structure and composition of anchoring sites significantly influence the catalytic performance of SACs even with the same metal element. Significant progress has been made to understand structure-activity relationships at an atomic level, but in-depth understanding in precisely designing highly efficient SACs for the targeted reactions is still required. In this review, various anchoring sites in SACs are summarized and classified into five different types (doped heteroatoms, defect sites, surface atoms, metal sites, and cavity sites). Then, their impacts on catalytic performance are elucidated for electrochemical reactions based on their distance from the metal center (first coordination shell and beyond). Further, SACs anchored on two typical types of hosts, carbon- and metal-based materials, are highlighted, and the effects of anchoring points on achieving the desirable atomic structure, catalytic performance, and reaction pathways are elaborated. At last, insights and outlook to the SAC field based on current achievements and challenges are presented.

The feasibility of utilizing electrochemical reduction of CO2 (CO2RR) to close the global carbon cycle is hindered by the absence of practical electrocatalysts that can be adopted in large CO2 emit...

Nickel oxide (NiO) with p-type semiconducting behaviour was prepared via a direct anodisation of nickel (Ni) foam followed by calcination treatment. This method offers a direct photoelectrode synthesis without the intermediate step using a pre-synthesised NiO powder. NiO photocathodes with modulated crystallinity were prepared under elevated calcination temperatures. The beneficial effect of having higher crystallinity in generating higher cathodic photocurrent became obvious in the aid of cadmium sulfide (CdS) deposition. It was found that CdS can promote the excited charge transportation of NiO towards water reduction, thus revealing the effect of NiO crystallinity modulation. The role of CdS as co-catalyst rather than a photosensitiser can be useful in the future design of photoelectrodes.

The storage and conversion of the surplus electricity generated by photovoltaic (PV) cells call for efficient electrochemical devices, such as water electrolyzers and metal–air batteries. Catalyst materials are normally the key in determining the efficiency of these devices, as the electrochemical processes involved are normally sluggish in reaction kinetics. Herein, we found that by encapsulating Ni, Co and Fe alloyed cores inside graphitic carbon shells (NiCoFe@C), a versatile catalyst material can be obtained, showing decent activity towards the oxygen evolution reaction (OER), oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). The encapsulation of the NiCoFe alloyed core induces the electronic structure change of the outer graphitic carbon shell, which tunes the binding strength of reaction intermediates thereby improving the catalytic activity.

The increasing interest in fuel cell technology and metal–air batteries has led to the need for stable and effective catalyst materials to replace noble metal (such as Pt) based benchmarks for the oxygen reduction reaction (ORR). In this study, carbon hollow spheres with highly dispersed nitrogen and phosphorus co-coordinated iron atoms (FeNPC) on their surface have been successfully fabricated, exhibiting exceptional ORR activity in both alkaline and acidic solutions. Specifically, the obtained FeNPC catalyst is capable of catalyzing the ORR with an onset potential of 1.03 V and a half-wave potential of 0.88 V (both vs. the reversible hydrogen electrode) in alkaline solution, outperforming the commercial Pt/C catalyst under identical conditions. Experimental results and theoretical simulations reveal that the quasi-octahedral O2-FeNxPy species are the active sites of the FeNPC composite. These species modify the electronic configuration of Fe centers and weaken the adsorption of the OH* intermediate, thereby promoting the ORR process. Additionally, the FeNPC catalyst also displays a catalytic activity towards the anodic oxygen evolution reaction (OER), making it an active air electrode catalyst in rechargeable Zn–air batteries with a high peak power density of 233.2 mW cm−2 and an excellent cycling stability at 3 mA cm−2 for over 15 h.

Identification of active sites for highly efficient catalysts at the atomic scale for water splitting is still a great challenge. Herein, we fabricate ultrathin nickel-incorporated cobalt phosphide porous nanosheets (Ni-CoP) featuring an atomic heterometallic site (NiCo16-xP6) via a boron-assisted method. The presence of boron induces a release-and-oxidation mechanism, resulting in the gradual exfoliation of hydroxide nanosheets. After a subsequent phosphorization process, the resultant Ni-CoP nanosheets are implanted with unsaturated atomic heterometallic NiCo16-xP6 sites (with Co vacancies) for alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The optimized Ni-CoP exhibits a low overpotential of 88 and 290 mV at 10 mA cm-2 for alkaline HER and OER, respectively. This can be attributed to reduced free energy barriers, owing to the direct influence of center Ni atoms to the adjacent Co/P atoms in NiCo16-xP6 sites. These provide fundamental insights on the correlation between atomic structures and catalytic activity.

The development of bifunctional water-splitting electrocatalysts that are efficient and stable over a wide range of pH is of great significance but challenging. Here, an atomically dispersed Ru/Co dual-sites catalyst is reported anchored on N-doped carbon (Ru/Co-N-C) for outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both acidic and alkaline electrolytes. The Ru/Co-N-C catalyst requires the overpotential of only 13 and 23 mV for HER, 232 and 247 mV for OER to deliver a current density of 10 mA cm

Zinc‐ion batteries (ZIBs) have attracted intensive attention due to the low cost, high safety, and abundant resources. However, up to date, challenges still exist in searching for cathode materials with high working potential, excellent electrochemical activity, and good structural stability. To address these challenges, microstructure engineering has been widely investigated to modulate the physical properties of cathode materials, and thus boosts the electrochemical performances of ZIBs. Here, the recent research efforts on the microstructural engineering of various ZIB cathode materials are mainly focused upon, including composition and crystal structure selection, crystal defect engineering, interlayer engineering, and morphology design. The dependency of cathode performance on aqueous electrolyte for ZIB is further discussed. Finally, future perspectives and challenges on microstructure engineering of cathode materials for ZIBs are provided. It is aimed to provide a deep understanding of the microstructure engineering effect on Zn2+ storage performance., Zinc‐ion batteries (ZIBs) have attracted intensive attention due to the low cost, high safety, and abundant resources. Recent advances regarding microstructural engineering on various ZIB cathode materials and the dependency of cathode performance on aqueous electrolyte for ZIBs are summarized. Future perspectives and challenges on microstructure engineering of cathode materials for ZIBs are also provided.

Controllable concomitant production of CO and H

Structure type and disorder have become important questions in catalyst design, with the most active catalysts often noted to be “disordered” or “amorphous” in nature. To quantify the effects of disorder and structure type systematically, a test set of manganese(III,IV) oxides was developed and their reactivity as oxidants and catalysts tested against three substrates: methylene blue, hydrogen peroxide, and water. We find that disorder destabilizes the materials thermodynamically, making them stronger chemical oxidants but not necessarily better catalysts. For the disproportionation of H2O2 and the oxidative decomposition of methylene blue, MnOx-mediated direct oxidation competes with catalytically mediated oxidation, making the most disordered materials the worst catalysts, whereas for water oxidation, the most disordered materials and the strongest chemical oxidants are also the best catalysts. Even though the manganese(III,IV) oxide materials were able to oxidize both methylene blue and peroxides direc...

Hydrogen peroxide produced by electrochemical oxygen reduction reaction provides a potentially cost effective and energy efficient alternative to the industrial anthraquinone process. In this study, we demonstrate that by modulating the oxygen functional groups near the atomically dispersed cobalt sites with proper electrochemical/chemical treatments, a highly active and selective oxygen reduction process for hydrogen peroxide production can be obtained in acidic electrolyte, showing a negligible amount of onset overpotential and nearly 100% selectivity within a wide range of applied potentials. Combined spectroscopic results reveal that the exceptionally enhanced performance of hydrogen peroxide generation originates from the presence of epoxy groups near the Co–N4 centers, which has resulted in the modification of the electronic structure of the cobalt atoms. Computational modeling demonstrates these electronically modified cobalt atoms will enhance the hydrogen peroxide productivity during oxygen reduction reaction in acid, providing insights into the design of electroactive materials for effective peroxide production., The production of hydrogen peroxide by electrochemical oxygen reduction is an attractive alternative to the industrial process, but catalysts should be optimized. Here, the authors enhance hydrogen peroxide production in acidic media with epoxy groups near cobalt centers on carbon nanotubes.

In this study, we prepared nitrogen-removed mesoporous carbon (NRMC) catalysts by applying various heat treatments to nitrogen-doped mesoporous carbon (NMC), which were applied as novel electrocata...

A well-ordered mesoporous SnO2 prepared by a simple and inexpensive nanocasting method was used as catalysts for the electrochemical reduction of CO2 to formate. The as-prepared catalyst exhibited high activity toward CO2 reduction, which was capable of reducing CO2 to formate with 38% of Faradaic efficiency (FE) at an applied overpotential as low as 325 mV. The maximum FE for formate generation (75%) was achieved at an applied potential of −1.15 V (vs RHE), accompanied by a high current density of 10.8 mA cm–2. The enhanced catalytic activity obtained with the mesoporous SnO2 electrocatalyst is attributed to its high oxygen vacancy defects (promotes CO2 adsorption and lowers overpotential) and crystallinity that provides sufficient active sites for CO2RR as well as its distinctive structural configurations which reduces impedance to facilitate faster CO2RR reaction kinetics.

The practical implementation of electrolytic water splitting systems (especially those powered by renewable energy resources, such as solar and wind) requires active and stable catalysts for the hydrogen evolution reaction (HER). The development of catalysts that can compete with, or exceed, the performance of the exorbitant platinum (Pt)-based benchmark is highly desirable. Here, we demonstrate the development of a highly active HER catalyst electrode, exhibiting Pt-like performances in both neutral electrolytes and natural seawater. The catalyst was obtained by pyrolysing a manganese-based metal organic framework (Mn-MOF) on nickel foam (Ni-F). We discovered for the first time that nickel foam not only acts as the substrate for catalyst growth but also provides nickel species that interact with the Mn-MOF, resulting in the formation of Mn doped nickel oxide/nickel hetero-structures on Ni-F (Mn–NiO–Ni/Ni-F). The potential utilization of this catalyst electrode for commercial applications was demonstrated in a self-customized water electrolyzer pack powered by photovoltaic cells.

In this work, we report a bifunctional electrocatalyst with nickel sulphide (Ni3S2) as the template, vertical graphene (VG) as the bridging material, and nickel–cobalt layered double hydroxides (NiCo LDHs) nanosheets as the active catalyst. The hybrid Ni3S2/VG@NiCo LDHs catalyst exhibits excellent activity in alkaline solution for both OER (overpotential ~ 320 mV at a current density of 100 mA cm-2) and HER (overpotential ~ 120 mV at a current density of 10 mA cm-2). In addition, the hybrid catalyst possesses superior stability with 99% retention of voltage upon a continued current density of 20 mV cm-2 for over 24 h. It is found that the transitions of Ni2+/Ni3+ and Co2+/Co3+ ions enable excellent HER and OER performances, and VG bridging between NiCo LDHs and Ni3S2, enable fast charge-transfer and a high density of active sites, resulting in the improved electrical conductivity, intrinsic activity, and electrochemical stability. This work provides a guideline to design the architecture of bifunctional catalysts for highly efficient water splitting applications.