3D Nanonetwork Research Articles

Electrochemical Performance of Titania 3D Nanonetwork Electrodes Induced by Pulse Ionization at Varied Pulse Repetitions.

Pulse ionized titania 3D-nanonetworks (T3DN) are emerging materials for fabricating binder-free and carbon-free electrodes for electrochemical energy storage devices. In this article, we investigate the effect of the one of the most important fabrication parameters, pulse frequency, for optimizing supercapacitor efficiency. A series of coin cell batteries with laser-induced electrodes was fabricated; the effect of pulse frequency on oxidation levels and material properties was studied using both experimental and theoretical analysis. Also, detailed electrochemical tests including cyclic voltammetry (CV), charge/discharge, and electrochemical impedance spectroscopy (EIS) were conducted to better understand the effect of pulse frequency on the electrochemical performance of the fabricated devices. The results show that at a frequency of 600 kHz, more T3DN were observed due to the higher temperature and stabler formation of the plasma plume, which resulted in better performance of the fabricated supercapacitors; specific capacitances of samples fabricated at 600 kHz and 1200 kHz were calculated to be 59.85 and 54.39 mF/g at 500 mV/s, respectively.

A 1D–3D interconnected δ-MnO2 nanowires network as high-performance and high energy efficiency cathode material for aqueous zinc-ion batteries

Aqueous zinc‐ion batteries (AZIBs) have received significant research attention and widely investigated because of their high intrinsic safety and cost effectiveness. Manganese dioxide has been regarded as a promising cathode material for AZIBs, attributed to its friendliness, abundant resources, high theoretical capacity, and high working voltage. Herein, a unique one-dimensional–three-dimensional (1D–3D) hybrid network with interconnected δ-MnO2 nanowires was reported as a cathode material for AZIBs. A distinctive 3D nano network structure resulted in enhancement of electrolyte osmosis and significant increase in contact between electrode and electrolyte, and also provided more active sites and convenient rapid ion transport routes. Moreover, the fine nanowire structure and the optimum layer spacing resulted in easier insertion/deinsertion of ion in the active material. Taking advantage of this feature, the δ-MnO2 cathode provides high reversible capacity, fast rate capability and good longevity for cycling. Further kinetic experiments revealed that Zn/δ‐MnO2 system constitutes an electrochemical reaction regulated by the combination of ionic diffusion and pseudo-capacitance; and shows high energy efficiency during the charge/discharge states. This research may provide an advanced cathode material for AZIB development.

3D periodic polyimide nano-networks for ultrahigh-rate and sustainable energy storage

A lithographic strategy to fabricate a 3D periodic nano-network of multi-electron redox-active polyimide is proposed, realizing ultrahigh rates up to 400C for lithium-ion storage of organic anodes.

Hybrid artificial neural networks and analytical model for prediction of optical constants and bandgap energy of 3D nanonetwork silicon structures

Hybrid artificial neural networks and analytical model for prediction of optical constants and bandgap energy of 3D nanonetwork silicon structures

High-Contrast Optical Modulation from Strain-Induced Nanogaps at 3D Heterogeneous Interfaces.

The realization of high‐contrast modulation in optically transparent media is of great significance for emerging mechano‐responsive smart windows. However, no study has provided fundamental strategies for maximizing light scattering during mechanical deformations. Here, a new type of 3D nanocomposite film consisting of an ultrathin (≈60 nm) Al2O3 nanoshell inserted between the elastomers in a periodic 3D nanonetwork is proposed. Regardless of the stretching direction, numerous light‐scattering nanogaps (corresponding to the porosity of up to ≈37.4 vol%) form at the interfaces of Al2O3 and the elastomers under stretching. This results in the gradual modulation of transmission from ≈90% to 16% at visible wavelengths and does not degrade with repeated stretching/releasing over more than 10 000 cycles. The underlying physics is precisely predicted by finite element analysis of the unit cells. As a proof of concept, a mobile‐app‐enabled smart window device for Internet of Things applications is realized using the proposed 3D nanocomposite with successful expansion to the 3 × 3 in. scale.

Chitin Nanofiber Paper toward Optical (Bio)sensing Applications.

Because of numerous inherent and unrivaled features of nanofibers made of chitin, the second most plentiful natural-based polymer (after cellulose), including affordability, abundant nature, biodegradability, biocompatibility, commercial availability, flexibility, transparency, and extraordinary mechanical and physicochemical properties, chitin nanofibers (ChNFs) are being applied as one of the most appealing bionanomaterials in a myriad of fields. Herein, we exploited the beneficial properties offered by the ChNF paper to fabricate transparent, efficient, biocompatible, flexible, and miniaturized optical sensing bioplatforms via embedding/immobilizing various plasmonic nanoparticles (silver and gold nanoparticles), photoluminescent nanoparticles (CdTe quantum dots, carbon dots, and NaYF4:Yb3+@Er3+&SiO2 upconversion nanoparticles) along with colorimetric reagents (curcumin, dithizone, etc.) in the 3D nanonetwork scaffold of the ChNF paper. Several configurations, including 2D multi-wall and 2D cuvette patterns with hydrophobic barriers/walls and hydrophilic test zones/channels, were easily printed using laser printing technology or punched as spot patterns on the dried ChNF paper-based nanocomposites to fabricate the (bio)sensing platforms. A variety of (bio)chemicals as model analytes were used to confirm the efficiency and applicability of the fabricated ChNF paper-based sensing bioplatforms. The developed (bio)sensors were also coupled with smartphone technology to take the advantages of smartphone-based monitoring/sensing devices along with the Internet of Nano Things (IoNT)/the Internet of Medical Things (IoMT) concepts for easy-to-use sensing applications. Building upon the unrivaled and inherent features of ChNF as a very promising bionanomaterial, we foresee that the ChNF paper-based sensing bioplatforms will emerge new opportunities for the development of innovative strategies to fabricate cost-effective, simple, smart, transparent, biodegradable, miniaturized, flexible, portable, and easy-to-use (bio)sensing/monitoring devices.

Highly Adjustable Three-Dimensional Hollow Pt(Au)Cu Nanonetwork Structures as Enhancing Electrocatalysts for Alcohol Oxidation Reaction

Pt-based nanomaterials are proven as one of the most efficient catalysts for direct alcohol fuel cells. However, it is a challenge to construct Pt-based catalysts with high catalytic activity and less Pt. In this work, we develop a new strategy to prepare three-dimensional (3D) nanonetwork structures (NNWs) like hollow Pt(Au)Cu (3D h-Pt(Au)Cu NNWs). 3D Cu nanonetworks (3D Cu NNWs) were firstly synthesized as template, and then by replacing Cu with Pt precursors or Pt and Au precursors, 3D h-Pt42Cu58 NNWs and 3D h-Pt38Au17Cu45 NNWs were obtained. Among the NNWs and commercial Pt/C, the 3D h-Pt38Au17Cu45 NNWs owned the best catalytic activity for methanol, ethanol and ethylene glycol oxidation reaction with the mass activity of 6.12 A mgPt−1, 8.53 A mgPt−1 and 12 A mgPt−1, which are 3.84-fold, 7.35-fold and 4.23-fold higher than that of commercial Pt/C. The study provides a simple strategy for preparing novel 3D hollow Pt-based polymetallic nanostructures, showing great potential in synthesizing and designing high-efficiency Pt-based electrocatalysts.

Morphology and characteristics of 3D nanonetwork porous starch-based nanomaterial via a simple sacrifice template approach for clove essential oil encapsulation

This study aimed at reporting on the nanoencapsulate clove essential oil (CEO) as natural food preservative and its enhancement in antimicrobial activities by 3D nanonetwork porous starch-based material (3D-NPS). 3D-NPS loaded CEO were fabricated via a sacrifice template approach using potato starch for the first time. The effects of the CaCO3 NPs concentration, encapsulation efficiency, temperature, and antimicrobial activity on the CEO-loaded 3D-NPS characteristics were investigated. The as-prepared 3D-NPS formed as the content of CaCO3 NPs/starch at 3:2 showed good uniformity and almost honeycomb shape, with channel diameters of about 200−300 nm. After encapsulation of CEO, the maximum encapsulation efficiency of CEO-loaded 3D-NPS reached 86.7 %, and it possessed enhanced stability against thermal treatment. The slow-release properties of CEO from 3D-NPS was describe exactly by the pseudo-first-order kinetics model. Moreover, the CEO loaded 3D-NPS not only revealed greatly enhanced antimicrobial activity against B. subtilis, S. aureus, and E. coli, but also significantly extended the duration of the antimicrobial activity of CEO. This novel method for the preparation of 3D-NPS is simple, non-toxic, and high-yield, exhibiting a promising platform for encapsulation and sustained release of unstable essential oils or other substances.

Surface enhanced 3D rGO hybrids and porous rGO nano-networks as high performance supercapacitor electrodes for integrated energy storage devices

Rapid advancements in technology has led to urgent requirement for mobile and portable power sources. Achieving self-sustainability using renewable energy sources using such devices provide an added advantage. Electrode materials play a critical role in performance of these devices, while the surface morphology of the electrode material play a crucial role in performance of electrodes themselves. Here we report fabrication of a flexible, all-solid state high performance hybrid supercapacitor using the 3D dendritic cell like nanostructures of Ni–Co LDH@rGO as cathode and novel crumpled leaf like rGO nano porous networks as anode. PVA-KOH gel is used as solid-state gel electrolyte. The fabricated supercapacitor is incorporated with a solar cell to demonstrate a self sustainable power pack The working potential window obtained is ∼1.4–1.8V. The asymmetric and hybrid assembly of the device enables in achieving high energy and power density. The energy and power density of the assembled supercapacitor is ∼58.4 Wh/Kg and ∼374 W/kg respectively at a current density of 0.5 A/g. The Coulombic efficiency is approximately 100% and suggests superior performance of the supercapacitor. Our experiments demonstrate the potential use of graphene based materials for powering wearable and portable electronic devices in a self sustainable manner.

Three-dimensional inorganic polymer of Pd aerogel as a highly active support-less anode catalyst toward formic acid oxidation

Metallic aerogels as a novel class of three-dimensional inorganic polymers have attracted a lot of attentions in academic researches. In this manuscript, an efficient way for the production of Pd aerogel is presented. The proposed way includes advantages such as one-pot synthesis, being fast, simple and surfactant free. The Pd aerogel is successfully synthesized by the reduction of H2PdCl4 with sodium borohydride followed by supercritical drying with liquid carbon dioxide. The extraordinary 3D network with the large porosity of Pd aerogel is confirmed by using TEM, FESEM, XRD, EDS, FT-IR and nitrogen isotherm techniques. The extraordinary 3D polymer is used as a support-less anode catalyst for the oxidation of formic acid. Based on the obtained results, the mass activity of 3D nanonetwork was estimated to be 1791.4 mAmg−1Pd, which was 2.67 times higher compared to Pd/C (668.5 mAmg−1Pd) nanocatalyst. Moreover, the Pd/C indicated a positive shift in onset potential, lower ECSA, greater Ea, greater RCT as well as weaker stability in comparison to the resultant aerogel. The exceptional catalytic behavior of 3D nanonetwork toward oxidation of formic acid was seriously affected by unique properties such as large porosity, high surface area as well as self-supporting characteristic of 3D nanonetwork.

Atomic Layer Deposition of Inorganic Thin Films on 3D Polymer Nanonetworks

Atomic layer deposition (ALD) is a unique tool for conformally depositing inorganic thin films with precisely controlled thickness at nanoscale. Recently, ALD has been used in the manufacture of inorganic thin films using a three-dimensional (3D) nanonetwork structure made of polymer as a template, which is pre-formed by advanced 3D nanofabrication techniques such as electrospinning, block-copolymer (BCP) lithography, direct laser writing (DLW), multibeam interference lithography (MBIL), and phase-mask interference lithography (PMIL). The key technical requirement of this polymer template-assisted ALD is to perform the deposition process at a lower temperature, preserving the nanostructure of the polymer template during the deposition process. This review focuses on the successful cases of conformal deposition of inorganic thin films on 3D polymer nanonetworks using thermal ALD or plasma-enhanced ALD at temperatures below 200 °C. Recent applications and prospects of nanostructured polymer–inorganic composites or hollow inorganic materials are also discussed.

Fabrication and electrochemical properties of 3D nano-network LiFePO4@multiwalled carbon nanotube composite using risedronic acid as the phosphorus source

LiFePO4@multiwalled carbon nanotubes (LFP@MWCNTs) nanocomposite has been fabricated using risedronic acid (RDA) as a new eco-friendly phosphorus source. Microscopic, spectroscopic, and electrochemical characterization demonstrate that the MWCNTs are in the form of coiled and cross-linking nanoribbon, which wrapped and encrusted around LiFePO4 particles to form a three-dimensional (3D) nano-network composite. This microstructure of 3D nano-network is obtained due to the reactions between RDA's special functional groups with Fe2+ and COH, CO or COOH on the surface of the functionalized MWCNTs. The results also show that the particle size of the fabricated LiFePO4@MWCNTs composite is below 300 nm with the pure crystal of olivine. This nanocomposite indicates an enhanced reversible capacity of 162.2 mAh g−1 at 0.2 C, and high capacity retention of 76.5% even at 10 C after the 800th cycles. The electric conductivity and Li+ diffusion coefficient (DLi+) of the LiFePO4@MWCNTs are 3.79 × 10−2 S cm−1 and 4.46 × 10−11 cm2 s−1, respectively. These improved electrochemical parameters can be attributed to the nano-sized effect of particles, MWCNTs' wrapping effect and 3D nano-network microstructure of the LFP@MWCNTs resulted from using RDA as a new phosphorus source.

Nanonetwork-structured yolk-shell FeS2@C as high-performance cathode materials for Li-ion batteries

Pyrite FeS2 is a promising alternative to typical intercalation cathodes for rechargeable lithium-ion batteries (LIBs) by virtue of its extremely high theoretical capacity. However, the inferior rate capability and fast capacity degradation caused by the sluggish reaction kinetics and large volume expansion upon lithiation greatly hinder its practical application. Herein, a chemical crosslinking strategy is developed for the synthesis of the yolk-shell pyrite FeS2@porosity-rich sulfur-doped carbon nanonetworks (FeS2@C NNs) as cathode materials for high-performance LIBs. The 3D nanonetwork structure constructed by tight covalent connection of carbon shells can act as highways to facilitate the electron transport kinetics, while the well-orchestrated internal cavities of the yolk-shell nanostructure provide large void space to accommodate the volume expansion of pyrite FeS2. In addition, the porosity-rich characteristic of carbon shells ensures fast pathways for the Li+ diffusion across the shells. As a result, the yolk-shell FeS2@C nanonetworks exhibit excellent high-rate capability (353 mAh g−1 at 10 C) and exceptionally long lifespan of 1000 cycles with a high capacity of 435 mAh g−1 at a large current density of 5 C, which is by far the best of pyrite FeS2-based cathodes for LIBs.

Fabrication of powdery polymer aerogel as the stationary phase for high-resolution gas chromatographic separation

Novel powdery polymer aerogel (PPA) prepared via the (micro)emulsion polymerization and the following hyper crosslinking reaction was fabricated as stationary phase of capillary column for the first time. Due to its powdery morphology, unique 3D nano-network structure, high surface area and good thermostability, the PPA-coated capillary column demonstrated high-resolution chromatographic separation towards nonpolar and weakly polar organic compounds, including benzene series, n-alkanes, ketone mixtures and trichlorobenzenes. Moreover, the reproducibility, quantitative analysis ability and thermostability of PPA-coated capillary column were also evaluated. The relative standard deviations for three replicate determinations of selected analytes were 0.02–0.11%, 0.12–0.26% and 1.2–3.6% for run-to-run, day-to-day and column-to-column analyses, respectively. The PPA demonstrated good thermostability, and the PPA-coated capillary column was proved to be heat-resistant (270 °C). The results of this study show PPA is an excellent candidate to be employed as stationary phase for gas chromatography capillary.

Design of reusable novel membranes based on bacterial cellulose and chitosan for the filtration of copper in wastewaters

This study has been carried out to design novel, environmentally friendly membranes by in situ and ex situ routes based on bacterial cellulose (BC) as a template for the chitosan (Ch) as functional entity for the elimination of copper in wastewaters. Two routes led to bionanocomposites with different aspect and physico-chemical properties. The mechanical behaviour in wet state, strongly related to crystallinity and water holding capacity, resulted to be very different depending on the preparation route although the Ch content was very similar: 35 and 37 wt% for the in situ and ex situ membranes, respectively. The morphological characterization suggested a better incorporation of the Ch into BC matrix through the in situ route. The cooper removal capacity of these membranes was analyzed and in situ prepared membrane showed the highest values, about 50%, for initial concentrations of 50 and 250 mg L−1. Moreover the reusability of the membranes was assessed. This is the first time that the whole 3D nano-network BC membrane is used to provide physical integrity for chitosan to develop eco-friendly membranes with potential applications in heavy metal removal.

PREDICTION OF IN-HOSPITAL MORTALITY AND LENGTH OF STAY IN ACUTE CORONARY SYNDROME PATIENTS USING MACHINE-LEARNING METHODS

BACKGROUND Nanomaterials offer greatly improved ionic transport and electronic conductivity compared with conventional battery and supercapacitor materials. They also enable the occupation of all intercalation sites available in the particle volume, leading to high specific capacities and fast ion diffusion. These features make nanomaterial-based electrodes able to tolerate high currents, offering a promising solution for high-energy and high-power energy storage. However, there are still many challenges associated with their use in energy storage technology and, with the exception of multiwall carbon-nanotube additives and carbon coatings on silicon particles in lithium-ion battery electrodes, the use of nanomaterials in commercial devices is very limited. After decades of development, a library of nanomaterials with versatile chemical compositions and shapes exists, ranging from oxides, chalcogenides, and carbides to carbon and elements forming alloys with lithium. This library includes various particle morphologies, such as zero-dimensional (0D) nanoparticles and quantum dots; 1D nanowires, nanotubes, and nanobelts; 2D nanoflakes and nanosheets; and 3D porous nanonetworks. Combined with lithium and beyond lithium ions, these chemically diverse nanoscale building blocks are available for creating energy storage solutions such as wearable and structural energy storage technology, which are not achievable with conventional materials. ADVANCES The success of nanomaterials in energy storage applications has manifold aspects. Nanostructuring is becoming key in controlling the electrochemical performance and exploiting various charge storage mechanisms, such as surface-based ion adsorption, pseudocapacitance, and diffusion-limited intercalation processes. The development of new high-performance materials, such as redox-active transition-metal carbides (MXenes) with conductivity exceeding that of carbons and other conventional electrode materials by at least an order of magnitude, open the door to the design of current collector–free and high-power next-generation energy storage devices. The combination of nanomaterials in hybrid architectures, such as carbon-silicon and carbon-sulfur, together with the development of versatile methods of nanostructuring, overcome challenges related to large volume change typical for alloying and conversion materials. These examples indicate that nanostructured materials and nanoarchitectured electrodes can provide solutions for designing and realizing high-energy, high-power, and long-lasting energy storage devices. OUTLOOK The limitations of nanomaterials in energy storage devices are related to their high surface area—which causes parasitic reactions with the electrolyte, especially during the first cycle, known as the first cycle irreversibility—as well as their agglomeration. Therefore, future strategies aim to develop smart assembly of nanomaterials into architectures with controlled geometry. Moreover, combining nanomaterials with complementary functionalities, such as high electronic conductivity of graphene or MXenes with high operating voltage and high redox activity of oxides, is necessary. Building sophisticated electrode architectures requires innovative manufacturing approaches, such as printing, knitting, spray deposition, and so on. Already-developed techniques such as 3D printing, roll-to-roll manufacturing, self-assembly from solutions, atomic layer deposition, and other advanced techniques should be used to manufacture devices from nanomaterials that cannot be made by conventional slurry-based methods. Such manufacturing approaches can also enable long-sought flexible, stretchable, wearable, and structural energy storage and harvesting solutions for Internet of Things and other disruptive technologies.

Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO₂ Gas Sensor.

Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO2 sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO2 sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO2 sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors.

Electrospun CeO2–Au nanofibers/graphene oxide 3D nanonetwork structure for the electrocatalytic detection of amlodipine

A novel electrochemical sensing platform based on CeO2–Au nanofibers (CeO2–AuNFs) and graphene oxide nanosheets (GO) is proposed for highly sensitive determination of amlodipine (AML) in aqueous media. The CeO2–Au hybrid nanofibers were prepared by the electrospinning technique and then annealed in air. The electrospun CeO2–AuNFs and GO were characterized by different techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), and Fourier transform infrared spectroscopy (FT–IR). The CeO2–AuNFs/GO-modified glassy carbon electrode) CeO2–AuNFs/GO/GCE (displayed excellent electrochemical catalytic activity toward the oxidation of amlodipine. Using differential pulse voltammetry (DPV), the prepared sensor showed good sensitivity for determining AML in two linear ranges of 0.01–10 and 10–1000 μmol L−1, with a detection limit of 2.5 nmol L−1. Electrochemical studies indicated that the CeO2–AuNFs/GO/GCE provided a synergistic augmentation on the voltammetric behavior of the electrochemical oxidation of AML. The proposed sensor was successfully applied for the determination of AML in human blood serum, plasma, and pharmaceutical samples with excellent recoveries and without the interferences of coexisting substances.

Building three-dimensional porous nano-network for the improvement of iron and nitrogen-doped carbon oxygen reduction electrocatalyst

Building three-dimensional (3D) nano-network and improving porous characteristics of nitrogen-doped carbon-based oxygen reduction electrocatalysts can facilitate to the diffusion of oxygen molecule and the enhancement of electrocatalytic performance. In this work, we report a new strategy for preparation of hemin-derived iron and nitrogen co-doped porous carbon electrocatalyst (3D-Fe/N/C-700) with three-dimensional nano-network via using a new hard template of inorganic salts (e.g., NaCl), followed by water-leaching and acid-leaching processes. This catalyst has exhibited a higher BET surface area (∼480 m2 g−1) and a larger total pore volume (∼0.49 cm3 g−1) compared to those of the Fe/N/C catalyst without using a NaCl template. An onset potential of ∼1.0 V vs. RHE and a high long-term stability are achieved for 3D-Fe/N/C-700, but a negative shift of only ∼30 mV exists in the half-wave potential of 3D-Fe/N/C-700 compared to the commercial 20 wt.% Pt/C catalyst. Besides, high electron transfer number (3.9 ± 0.2) and low peroxide species (<18.5%) on 3D-Fe/N/C-700 in the potential range of 0.2–0.8 V indicate a quasi four-electron pathway for electroreduction of O2 molecule. We also suggest that the FeN2 structure may be the active center of our catalyst, but 3D porous network and graphitic-N can play an important role in the enhancement of ORR electrocatalysis. Sustainable conversion of hemin to nitrogen-doped porous carbon and recyclability of NaCl template render a scalable production and practical application of carbon materials for energy storage and conversion.

3D nickel-cobalt diselenide nanonetwork for highly efficient oxygen evolution

Active, stable and low-cost oxygen evolution reaction (OER) catalyst for electrochemical water splitting is key to efficient energy conversion and storage. Here, we report a three-dimensional (3D) nanonetwork as noble-metal-free electrode consisting of nickel cobalt diselenide (NiCoSe2) nanobrush arrays on Ni foam (NF) through the initial hydrothermal reaction and subsequent thermal selenization process. Introducing ammonium fluoride as surface controller, different NiCoSe2 hierarchical architecture can be modulated from nanorods, nanobrush to nanosheets. The unique brush-like NiCoSe2 possesses high surface area for mass transfer, rough surface with rich active sites, 3D nanostructure preventing the accumulation of O2 bubbles. Compared to NiCoSe2 nanorods/NF, NiCoSe2 nanosheets/NF and commercial RuO2, NiCoSe2 nanobrush/NF exhibits an enhanced OER performance in alkaline media to reach a low overpotential of 274mV at the current density of 10mA/cm2, small Tafel slope and a long-term stability. The developed 3D nanonetwork highlights the nanoscale engineering and offers a promising alternative to noble metal catalysts for electrochemical water oxidation.