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A self-strengthening coating with silver nanoparticles (Ag NPs) doped chitosan (CHI) and sodium alginate (SA) polyelectrolytes was constructed on the surface of polydopamine (PDA) coated Ti substrate by a layer-by-layer assembly method. The PDA coating exhibited an excellent bond with Ti substrate, and also can uniformly deposit Ag NPs via a mild method without introducing any exogenous reductant. The CHI coating was assembled through a spin-coating method for controlling Ag+ release. The SA was introduced to enhance the anticorrosion performance by forming calcium alginate (CA) in a corrosive medium. The corrosion protection was investigated with electrochemical impedance spectroscopy and polarization curves tests in fluorine-containing artificial saliva. During immersion, the charge-transfer resistance and the protection efficiency (ŋ) presented a continuous increase with the immersion time, demonstrating that this coating possessed a remarkable self-strengthening capability, and the compositions of the outermost film changed from SA to CA with the Ca2+ cations of the corrosive medium as a crosslinker by SEM and EDS analysis. Furthermore, the ŋ remained up to 96.8% after immersion of 30 days, and then the coating also displayed a distinct inhibition zone on S. mutans. These results prove this coating possesses an excellent anticorrosion performance and antibacterial property.

The influence of mercury on the morphology and formation mechanism of gold amalgams in the presence of different reducing agents (ascorbic acid and sodium borohydride) was systematically studied. In the presence of cetyltrimethylammonium bromide (CTAB), chemical reducing agents not only reduced mercury ions in the solution but also replaced the CTAB molecules on the surface of the gold nanorod. The stability of the reducing agents in the colloidal system and the combining capacity of the reducing agent to the gold nanoparticles can affect the alloying process of mercury and gold, thereby forming a rod-shaped or spherical gold amalgam. Once CTAB was removed, a similar transformation process occurs between the gold nanorods and mercury. In addition, without the presence of a stabilizer, mercury that cannot be dispersed undergoes Ostwald ripening growth, which causes the gold amalgam nanoalloys to form a tip-to-tip structure as a result of mercury enrichment because of the weak shielding effects occurring at the tips of the gold nanorods. After the CTAB molecules were substituted with ascorbic acid and alkylthiol molecules, the question of whether the shielding effect weakened or disappeared was also investigated. By investigation, this research found that, in comparison to the blocking effect of CTAB molecules, the binding ability of the reducing agent to gold plays a dominant role in the nanoamalgam formation process.

A series of gold nanoparticles were synthesized by stepwise growth method under the condition of citrate as a reducing agent and stabilizer. The optical properties with the maximum absorption wavelength (λmax) and electrochemical properties of the oxidation potential (Ep) dependence on the particle size were analyzed. The method of calculating the particle size from the UV-visible spectrum and the electrochemical oxidation peak was deduced, following the theoretical prediction trend and consistent with previous observations. Furthermore, we investigated the application performance based on the electrochemical catalytic activity and the aggregation of the spherical gold nanoparticles using L-cysteine as a target. The results indicated that the optical and electrochemical properties of the gold nanoparticles to L-cysteine were closely related to the particle size of gold nanoparticles. With the increased size of the nanoparticles, the full width at half maximum in the UV-visible absorption spectrum increased and the electrochemical oxidation potential was positively shifted.

Pretreatment layers have attracted much attention due to their irreplaceable role in paint system. However, the commonly used pretreatment layers face with one common problem, which the environmental friendliness and excellent properties can not be simultaneous realization. This work reported one facile method to synthesize one stable polyacrylic acid/Ca nanoparticles hybrid hydrosol through the electrostatic interaction between polyacrylic acid and Ca 2+ . Ulteriorly, the fabricated stable hydrosol was utilized as one environmentally friendly pretreatment layer material to fabricate new generation pretreatment layer on cold-roll steel surface through immersion method. The electrochemical and microstructure results indicated that the polyacrylic acid/Ca hybrid hydrosol based pretreatment layer exhibited better anti-corrosion performance and higher root mean square roughness value than polyacrylic acid layer. Meanwhile, neutral salt spray test results reflected that the polyacrylic acid/Ca hybrid pretreatment layer based coating system exhibited better service performance than the no pretreatment or polyacrylic acid layer based coating system. Because of the environmental friendliness, good anti-corrosion performance and higher root mean square roughness value, the polyacrylic acid/Ca nanoparticles hybrid hydrosol based pretreatment layer are expected to act as substitutes for chromate and phosphate conversion layers and will find widespread application in metal surface pretreatment field.

Silanes and organophosphorus compounds have been widely used in the field of corrosion inhibition. Herein, two corrosion inhibitors containing multiple phosphate groups and different silane groups, namely, 1,3-bis{3-[N-(1-phosphonatediethyl)-isopropyl] aminopropyl}-1,1,3,3-tetramethyldisiloxane (BPIAT) and N,N-di-methylenephosphonate-aminopropyl dimethyl silanol (DMADS), were designed and their corrosion inhibition properties on the iron surface in 0.5 M H2SO4 solution were characterized by polarization curves and electrochemical impedance spectroscopy (EIS) at 25 °C. In order to further analyze the corrosion mechanism thoroughly, three organophosphorus compounds without silane groups, namely, Hexamethylene-diamine tetra(methylene phosphonic acid) (HDTMPA), (ethylenedinitrilo)-tetra methylene phosphonic acid (EDTMP), and diethyl 1-decylphosphonate (DDP), were also investigated. The electrochemical experimental results reveal that five corrosion inhibitors are mixed type inhibitors and the adsorption process obeys Langmuir isotherm, and the corrosion inhibition efficiency of BPIAT and DPSD is significantly higher than that of HDTMPA, EDTMP and DDP. A new corrosion inhibition mechanism was proposed by comparing the corrosion inhibition performance of five corrosion inhibitors. The corrosion inhibitors are absorbed on the iron surface by Fe-O-P covalent bonds and Van Der Waals’ force. Simultaneously, the Si-O-Si structure is conducive to the improvement of the corrosion inhibition efficiency.

Self-strengthening HEDP-Zn films were constructed on the CRS surface and the corrosion protection was afforded by electrochemical impedance spectroscopy (EIS) tests. After immersion in NaCl solution, HEDP-Zn-coated CRS underwent three stages: strengthening, balance and weakening. During immersion, a portion of unstable HEDP-Zn complexes were destroyed, accompanied by the intercalation and departure of Na + , thereby resulting in the changes in microstructure, chemical compositions and thickness of the films. Thus, anticorrosion performance increased due to the increased surface coverage by the complexes and additional binding sites during the first stage but decreased because of the reduced film thickness in the third stage.

The development of water splitting technology is severely impeded by the limited strategies for preparing efficient photocatalyst with optimal structure. Herein, a facile structure and doping engineering strategy is proposed to obtain the atomic-thin mesoporous graphite carbon nitride (g-C3N4) nanosheets with a large specific surface area of 212.5 m2 g−1, an ultra-large pore volume of 1.55 cm3 g−1, high C and O contents of ∼51.4 and 4.8% via an acid-assisted exfoliation route without any hard templates. The theoretical calculation reveals that the introduction of additional C/O atoms into g-C3N4 matrix would boost the charge transfer rate and charge separation efficiency due to the enhanced electronic polarization effect (Bader Charge) and shortened bond lengths. Additionally, the electronic conductivity is demonstrated to be enhanced due to the formation of delocalized π-bonding both experimentally and theoretically. The synergic contribution of textural and electronic features renders an excellent photoelectrochemical (PEC) performance with 50–60 times larger photocurrent in comparison with the pristine g-C3N4 and high hydrogen evolution rates of 830.1 and 115.5 μmol g−1 h−1 under the solar- and visible-light irradiation, respectively. This in-situ exfoliation approach demonstrates a facile yet efficient method to synthesize highly porous carbon nitride materials with optimal structure and composition for efficient water splitting.

A flexible electrode based on polypyrrole-supported free-standing molybdenum oxide-molybdenum disulfide/polypyrrole nanostructure (MoO3–MoS2/PPy) was synthesized. The petal-like MoO3–MoS2 sheets grown on PPy were prepared step by step through simple electrodeposition and hydrothermal methods. The corresponding surface morphological and structural characterizations were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the prepared petal MoO3–MoS2 hybrid nanomaterials were uniformly distributed on the PPy skeleton and exhibited a three-dimensional porous network structure. The flexible electrode was used for non-enzymatic detection of hydrogen peroxide (H2O2), and the developed MoO3–MoS2/PPy nanomaterials exhibited high electrochemical sensing performance in the range of 0.3–150 μM, with the detection limit of 0.18 μM (S/N = 3). The excellent detection properties enabled the MoO3–MoS2/PPy flexible electrode to detect H2O2 released by living cells. The resulting MoO3–MoS2/PPy flexible electrode also has the advantages of customizable shape and adjustability, which provides a potential platform for constructing clinically diagnosed in vivo portable instruments and real-time environmental monitoring.

Aqueous rechargeable zinc-based batteries are attractive as promising candidates for practical electric vehicles. However, such batteries still suffer from the poor cycling stability and potential safety issue due to the dendrite formation. Herein, we design three-dimensional (3D) graphene foams co-doped with sulfur and nitrogen via an in-situ reduction of graphene oxide and subsequent thermal annealing process. Performed as both cathodic and anodic matrixes, the unique features of 3D porous graphene framework with N, S co-doping not only enable the reversible plating/striping process of zinc, but also facilitate the redox reactions of iodine species. Thus, the rationally designed aqueous rechargeable zinc-iodine system can integrate the redox reactions of zinc and iodine redox couple at the interface of graphene foam and electrolytes along with reversible ion shuttles (e.g., Zn2+, I−/I3−) for efficient energy storage. More importantly, the 3D porous architecture with N, S co-doping can enhance the battery Coulombic efficiency by shortening the potential gap of charging/discharging process and suppress the formation of zinc dendrites by improve the reaction kinetics of reversible redox reactions.

Polyacrylic acid (PAA)–metal complex-based hybrid films with favorable anticorrosion performance were constructed directly on iron substrates. Thus, a high affinity of PAA for oxidized iron surface and its strong complexation ability to metal ions were fully used. The self-assembled PAA layer was first prepared on iron substrates by self-assembled PAA polymer in alcohol–water mixed solution. Despite a relatively poor anticorrosion performance, the as-prepared self-assembled PAA layer could be used as a functional bottom layer to fabricate PAA–metal complex films because PAA can strongly complex metal ions. Here, organic PAA films were further functionalized by directly immersing PAA film-coated iron specimens in aqueous solutions containing Ce3+ or Zn2+ or both metal ions to allow the complexation reaction between PAA and metal ions to proceed spontaneously. The obtained PAA–M (M = Ce, Zn here) hybrid films could more strongly suppress the corrosion of iron substrates in NaCl corrosive solution than organic self-assembled PAA films. PAA–Zn films exhibited the strongest corrosion protection ability, as exemplified by the appearance of only one time constant related to resistance and capacitance of hybrid films in the impedance spectra. In the mixed solution of Ce3+ and Zn2+ ions, the presence of Ce3+ could significantly promote the combination of Zn2+ with PAA polymers. However, as-fabricated PAA–Ce–Zn hybrid films showed impedance behavior quite differently from that of PAA–Zn films. This study is helpful in designing and fabricating environmentally friendly organic–inorganic hybrid conversion coatings with excellent anticorrosion performance.

Potassium-ion batteries (KIBs) have emerged as attractive alternatives to dominative lithium-ion batteries for grid-level electricity storage due to lower potential of K+/K redox couple in non-aqueous electrolyte and abundant potassium resource. The current intercalation cathodes used in KIBs provide limited active sites in their frameworks while conversion chemistry offers the feasibility for much improved potassium-ion storage capability. We for the first time demonstrate a rechargeable potassium-iodine (K-I2) battery enabled by a two-electron K-I2 conversion reaction. With the help of in-situ Raman and ex-situ X-ray photoelectron spectroscopy, we confirm that the highly reversible conversion among I2, KI3 and KI involves solid-liquid-solid phase transitions and the formation of soluble KI3 intermediate enables the fast reaction kinetics. The K-I2 battery delivers a reversible capacity of 156 mA h/g and a small capacity decay of 0.058% per cycle over 500 cycles.

Molybdenum sulfide nanosheets on nitrogen-doped carbon nanowires (MoS2/CN NWs) were utilized to construct an electrochemical biosensor for hydrogen peroxide (H2O2). Polypyrrole nanowires (PPy NWs) were synthesized using a surfactant-assisted method, and few layers of MoS2 nanosheet grew on PPy NWs by a hydrothermal approach. After a sintering process, the prepared MoS2/CN nanohybrid was supposed to enhance the electrochemical catalytic performance for H2O2 resulting from the synergistic effect between the high stability of CN NWs and abundant active sites of MoS2 nanosheets. The CN NWs served as the framework for the few-layered MoS2 to form a core-shell structure which could increase the stability and electrochemical conductivity of MoS2 nanocomposite. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the crystallinity of MoS2 and the nitrogen-doped carbon nanowires. The electrochemical responses showed that the MoS2/CN NWs modified electrode has a good catalytic performance toward H2O2 determination with a wide linear range from 2 to 500 μM, and a low detection limit of 0.73 μM (S/N = 3). Moreover, the fabricated electrochemical biosensor performed monitoring of H2O2 released from A549 living cells, indicating that the MoS2/CN NWs offered a simple and convenient pathway in the fields of electrochemical sensing.

A coordination-induced film-forming method was developed to construct 2-hydroxyphosphonoacetic acid (HPAA)-Zn2+ complex conversion layer (HPAA-Zn2+ layer for short) on cold-rolled steel (CRS) substrate. Moreover, the incorporation of Mo component into the HPAA-Zn2+ layer can significantly improve the uniformity and anticorrosion properties. The results showed that Mo-incorporated HPAA-Zn2+ layer displayed the best anticorrosion performance when the molar ratio of HPAA/Zn2+ was 1:1, the film-forming time was 10 min, and the concentration of molybdate was 0.1 wt%. In addition, energy dispersive spectroscopic (EDS) and X-ray photoelectron spectroscopic (XPS) results demonstrated that the Mo-incorporated HPAA-Zn2+ layer was mainly composed of ZnO and HPAA-Zn2+ complex and also confirmed that Mo-O-P bonds occurred between molybdate anion and HPAA molecule.

Seeing that amino trimethylene phosphonic acid (ATMP) possesses very strong complexation ability to metal ions and the phosphonic acid group has good affinity for the oxidized iron surface, herein a simple and rapid film-forming method (one-step assembly method) was developed to construct the ATMP-Zn complex conversion layers (ATMP-Zn layers for short) on the cold-rolled steel (CRS) substrate. Zinc ions were found to participate in the formation process of ATMP-based composite film, which made the Zn-containing ATMP film significantly different in appearance, thickness, microstructure and film-forming mechanisms from the Zn-free ATMP film. There was mainly iron (ш) phosphonate in the Zn-free ATMP film, whereas there were Zn2+-ATMP complex and a certain amount of ZnO in the ATMP-Zn composite film. In addition, electrochemical test results clearly indicate that corrosion resistance of ATMP-Zn composite film was greatly enhanced due to the presence of Zn component. Moreover, the corrosion resistance performance could be controlled by adjusting film-forming time, pH and ATMP concentration in the film-forming solutions. The present study provides a new method for the design and fabrication of high-quality environmentally-friendly conversion layers.

Amorphous phytic acid nanoparticles were prepared via a condensation reaction of phytic acid with aminopropyltriethoxysilane. X-ray photoelectron spectroscopy and fourier transform infrared characterizations demonstrated that there were abundant phosphate groups on the surface of as-prepared phytic acid nanoparticles. The advanced composite phytic acid nanoparticles doped silane sol-gel coating was fabricated on the cold-rolled steel substrates using sol-gel technique and introducing phytic acid nanoparticles into the coating. The results of electrochemical tests showed that the doping of phytic acid nanoparticles greatly improved the anti-corrosion and durable performances of the silane coatings. The simple strategy which utilized the “active” nanoparticles to improve the corrosion mitigation and durable performances of coating is expected to find wide application in the anti-corrosion coating industry.

In this work, a novel CoO/CoFe2O4 bi-component nanorod coated with S-doped carbon nanospheres shell (CO/CFO@SC Nr) composites have been synthesized through one in-situ polymerization and subsequent annealing treatment. The S-doped carbon shell, special structure and synergistic effect between CoO and CoFe2O4 significantly enhance the electrochemical performance of the CoO/CoFe2O4 anode material. CO/CFO@SC Nr composites present an impressive capacity of 511.3 mAh g−1 after 700 cycles when tested at a high current density of 2000 mA g−1. In addition, this is the first time that polythiophene is used as sulfur and carbon source to synthesis transition metal oxide (TMO) @S-doped carbon core-shell composites. This work illuminates a new preparation way for fabrication other TMO@S-doped carbon core-shell materials for lithium-ion batteries and other energy storage devices.

The design of a flexible electrode based on carbon cloth (CC) which can solve the problem of the weak coupling effect and binding force between the substrate and active materials has stimulated intensive research on configuring supercapacitors with these materials to achieve high energy and power densities. In this paper, a N,P-doped carbon (NPC) layer as an intermediate layer is sandwiched between the active materials and carbon cloth, which can not only enable the stable and homogeneous growth of active materials on the carbon fiber but also maintain the long cycle life of the flexible electrode in supercapacitors owing to its rich structural defects, excellent hydrophilic characteristics and mechanism of heteroatom doping. Such a sandwiched flexible electrode consisting of bimetallic sulfide (BS), an N,P-doped carbon layer and carbon cloth (denoted as CC–NPC–BS) is assembled as a positive electrode in a solid-state asymmetric supercapacitor (ASC) device, which delivers a high energy density of 56.7 W h kg−1 at a power density of 1.5 kW kg−1 and has outstanding long cycling stability with 85% capacitance retention after 15 000 cycles.

A nickel-cobalt-sulfide nanosheet (Ni-Co-S NS)/polypyrrole nanowire (PPy NW) core/shell-structured composites on nickel foam (NF) was synthesized by facile electrodeposition processes for electrochemical non-enzymatic glucose sensor. PPy NWs grew on the NF substrate by a potentiostatic deposition method, and then the PPy NWs were further served as skeletons for electrodeposition Ni-Co-S nanosheets. The ternary Ni-Co-S NSs as the shell and PPy NWs as the core on the flexible NF constructed the 3D micro/nano structure. The as-prepared Ni-Co-S/PPy/NF electrode was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). The electrochemical sensor was used for the detection of glucose by chronoamperometry. The introduction of the interconnected Ni-Co-S NSs can provide accessible pathways for electrolyte and have high sensitivity to glucose. Compared with the NF and PPy/NF electrodes, the Ni-Co-S/PPy/NF micro/nanohybrid electrode exhibited higher catalytic activity towards electro-oxidation of glucose. The developed Ni-Co-S/PPy/NF electrode showed two linear electrochemical responses to glucose in the range from 2 μM to 140 μM with a correlation coefficient of R2 = 0.937 and 0.14 mM to 2 mM with a correlation coefficient R2 = 0.978, and the detection limit is 0.82 μM. Furthermore, the prepared biosensor demonstrated high selectivity to glucose in the presence of uric acid, ascorbic acid and D-fructose.

For the wearable and flexible applications, solid-state supercapacitors have been attracted significant attention owing to their unique features. Herein, we demonstrated the fabrication of a high-energy solid-state hybrid supercapacitor by using cobalt hexacyanoferrate nanoparticles and molybdenum oxide thin films grown on the flexible carbon fiber cloth. The flexible hybrid supercapacitor using a neutral gel electrolyte can be operated in a stable potential window of 2.0 V and delivers a maximal energy density of 67.8 Wh kg−1 at the power density of 1003 W kg−1, outstanding reliability without capacitance degradation under various twisting rates, and remarkable cycling stability retaining 74% of initial capacitance after 10000 cycles.

Many fundamental researches about the effect of some basic properties of a pre-treatment layer, such as anti-corrosive performance, surface roughness and chemical composition on the overall performance of paint systems were investigated. Three kinds of pre-treatment layers: bare polyacrylic acid (PAA) layer, Mo based layer and Mo doped PAA layer were deposited on cold-rolled steel surfaces through immersing the steel samples in the corresponding solution. The electrochemical measurements results indicated that after been treated in PAA solution, the steels became vulnerable to corrosion and the Mo based layer and Mo doped PAA layer could improve the corrosion resistance of steel to a certain degree. The values of root-mean-square roughness of the bare steel, bare PAA layer, Mo based layer and Mo doped PAA layer were 15.0 nm, 11.3 nm, 13.0 nm and 59.1 nm, respectively. The corresponding values of arithmetic average roughness of the samples were 16.9 nm, 10.5 nm, 9.1 nm and 41.0 nm, respectively. The spectroscopy results indicated that the surface of the bare PAA and Mo doped PAA layer covered steels contained abundant COOH groups and the composition of Mo based layer covered steel surface was mainly oxides. According to the impact test and neutral salt spray test results, the corrosion mitigation performance, microstructure and chemical composition of the pre-treatment layer could all affect the overall performance of the paint system. All the results indicated that the anti-corrosive performance was not the only index, the microstructure and chemical composition also needed to be considered in the development of a new generation pre-treatment layer.

Exploring highly efficient and durable bifunctional electrocatalysts from earth-abundant low-cost transition metals is central to obtaining clean hydrogen energy through large-scale electrolytic water splitting. Porous nickel–cobalt nitride nanosheets on macroporous Ni foam (NF) are synthesized through facile electrodeposition followed by a one-step annealing process in a NH3 atmosphere. The transformation from a metal hydroxide into a metal nitride could efficiently enhance the electrocatalytic performance for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Interestingly, the incorporation of nickel further boosts the catalytic activity of cobalt nitride. When used as bifunctional electrocatalysts, the obtained nickel–cobalt nitride electrocatalyst shows good stability and superior catalytic performance toward both HER and OER with low overpotentials of 0.29 and 0.18 V, respectively, to achieve a current density of 10 mA cm−2. The good electrocatalytic performance was also evidenced by the fabrication of an electrolyzer for overall water splitting, which exhibits a high gas generation rate for hydrogen and oxygen with excellent stability during prolonged alkaline water electrolysis. The present work provides an efficient approach to prepare a 3 D interconnected porous nickel–cobalt nitride network with exposed inner active sites for overall water splitting.

Phytic acid conversion coating and Zn2 + doped phytic acid conversion coating were fabricated on Q235 steels by immersing the steel samples in corresponding coating bath for 600 s. The changes of coating formation process and adsorption action of phytic acid on steel surface due to addition of Zn2 + in coating bath were investigated. Scanning electron microscopy images exhibited that phytic acid conversion coating was porous network structure consisting of needle-like crystals, but Zn2 + doped phytic acid conversion coating was one uniform layer except some fine cracks. Energy dispersive spectroscopic, X-ray diffraction and X-ray photoelectron spectroscopic characterizations demonstrated that the roles of Zn2 + during the coating formation process could conclude to two sides: (i) Zn2 + could promote the adsorption reaction of phytic acid to form one thicker phytic acid conversion coating on steel surface; (ii) a part of Zn2 + could form ZnO and aggregation of the complex of phytic acid, Zn and Fe and doped to the formed conversion coatings. And the electrochemical measurements results showed that the corrosion protection efficiency of Zn2 + doped phytic acid conversion coating was higher than that of phytic acid conversion coating.

This paper describes stable and highly dispersed aqueous colloids of polyaniline (PANI) nanofibers that were prepared by a chemical method and used to modify a glassy carbon electrode (GCE). The materials combines the good electrical conductivity and network structure of PANI nanofibers with the complexing capacity of mercaptosuccinic acid. The modified GCEs exhibit high sensitivity to Cd(II) and Pb(II) ions, with detection limits of 50 ng·L−1 and 200 ng·L−1, respectively. The modified GCE was applied to the simultaneous determination of the cancer biomarkers carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) by using particles of metal-organic frameworks (MOFs) prepared from Pb(II) or Cd(II) and 2-aminoterephthalic acid. The particles are used as electrochemical labels for secondary anti-CEA and secondary anti-AFP antibody in a sandwich assay. The two ions in the MOFs labels on the secondary antibody can be detected best at voltages of −0.63 and −0.88 V (vs Ag/AgCl), respectively. The assay has a linear response in the 0.3 pg·mL−1 to 3 ng·mL−1 concentration range of both CEA and AFP, and the respective detection limits are 0.03 pg·mL−1 and 0.1 pg·mL−1. In our preception, this assay has a wide scope in that it may be applied to a variety of sandwich types of immunoassays.

A hierarchical porous CoO/Cu2O nanoarray assembled on three-dimensional Cu foam was successfully fabricated by a facile solution-phase cation exchange technique. The morphology and crystalline structure of the target composite were optimized by investigating the sintering conditions. The unique bimetallic oxides demonstrate a secondary porous structure on primary nanoarrays, which facilitated the electrolyte permeation and decreased the ionic transport distance. Owing to the conductive Cu framework and synergistic biactive components, the as-prepared composite displayed superior electrochemical performance with high capacity and rate capability. Moreover, it showed stable cycling performance and a capacity of 832 mAh g−1 even after 50 discharge/charge cycles. The ionic transfer kinetics were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The cycled electrodes were also carefully examined to explain the origin of the enhanced performance. With a superb electrochemical performance and facile fabrication route, the freestanding CoO/Cu2O composites have a promising future as next-generation anodes for lithium–ion batteries.

In polymer nanocomposites, particle-polymer interactions influence the properties of the matrix polymer next to the particle surface, providing different physicochemical properties than in the bulk matrix. This region is often referred to as the interphase, but detailed characterization of its properties remains a challenge. Here we employ two atomic force microscopy (AFM) force methods, differing by a factor of about 15 in probing rate, to directly measure the surface nanomechanical properties of the transition region between filler particle and matrix over a controlled temperature range. The nanocomposite consists of poly(ethyl methacrylate) (PEMA) and poly(isobutyl methacrylate) (PiBMA) with a high concentration of hydrophobized silica nanoparticles. Both AFM methods demonstrate that the interphase region around a 40-nm-sized particle located on the surface of the nanocomposite could extend to 55-70nm, and the interphase exhibits a gradient distribution in surface nanomechanical properties. However, the slower probing rate provides somewhat lower numerical values for the surface stiffness. The analysis of the local glass transition temperature (T

An electrochemical aptasensor for the lipopolysaccharide (LPS) detection was constructed by using copper-based metal-organic framework (Cu-MOF) as a label and the LPS aptamer of specific single-stranded DNA as a probe. The carboxyl-functionalized polypyrrole nanowires (PPy NWs) were synthesized by electrochemical polymerization method, and the amino-terminated aptamer covalently coupling with the carboxyl group of the PPy NWs was immobilized onto the modified electrode. The aptamer can specifically combine with the target LPS molecules, and Cu-MOF was labeled by adsorption based on specific interactions of LPS carbohydrate portions with anionic groups. The fabrication processes of the aptasensor were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to measure electrochemical performance of the aptasensor, and the electrochemical signal can be directly measured by the electrochemical redox reaction of Cu(II)/Cu(I) existed in the Cu-MOF. The electrochemical aptasensor exhibited a high sensitivity toward LPS ranging from 1.0 pg/mL to 1.0 ng/mL with a detection limit of 0.29 pg/mL. Moreover, the developed sensor was found to have good selectivity, stability and regeneration properties, and the sensor also successfully detected LPS in real tap water samples.

Improving surface selectivity and maximizing electrode surface area are critical needs for the electroreduction of nitrate. Herein, preferential (100) oriented Pt nanoflowers with an extended surface area were prepared by potentiostatic deposition on carbon cloth (Pt NFs/CC), and then Cu atoms were adsorbed on the Pt NFs (Cu/Pt NFs/CC) for application of nitrate electroreduction. The results reveal that Cu/Pt NFs/CC with 8.7% Cu coverage exhibits a high selectivity for nitrate electroreduction to N2 following two steps: Nitrate firstly converts into nitrite on Cu sites adsorbed on Pt NFs, then nitrite subsequently selective reduction and ammonia oxidation to N2 occur on the large exposed (100) terraces in Pt NFs. In addition, electrocatalytic activity and selectivity of nitrate reduction strongly rely on the Cu surface coverage on Pt NFs, the lower activity of nitrate reduction is displayed with increase of Cu coverage. Accordingly, the selective reduction of nitrate to N2 is feasible at such nanostructured Pt nanoflowers modified with Cu.

Because traditional chromating and phosphating processes are harmful to the environment and human health, an eco-friendly tannic acid (TA)-based conversion film technology is established by adopting a new self-assembly strategy of TA/metal complexes on iron surfaces in aqueous solutions. In this study, TA and TA/Zn films were conveniently fabricated by anchoring a certain amount of TA molecules on the iron surface through the coordination interaction between phenolic hydroxyls and metal ions. In contrast, the introduction of Zn ions in the film-forming process cannot only complex with more TA molecules to form a thicker conversion film but also accelerate the film-forming process and transform into ZnO, which can further inhibit iron corrosion. This combination leads to the excellent corrosion protection of TA/Zn film-modified iron (the corrosion protection efficiency is up to 92.39%). Moreover, impact tests show that the TA/Zn film can enhance the adhesion between the iron substrate and outer coating.

A polyelectrolytes coating with self-healing and self-strengthening dual-function was fabricated on the titanium sheet for anticorrosion studies in fluorine-containing artificial saliva. The coating contains a polydopamine bottom film and 2-hydroxypropyltrimethyl ammonium chloride chitosan and sodium alginate multilayers. The incorporated polydopamine bottom film was modified to assure the adhesion of the polyelectrolytes coating on the titanium sheet. Based on the scratch assay, there are two stages for the scratched coating immersed in fluorine-containing artificial saliva: healing and strengthening. Results exhibited that the coating possesses a remarkable self-healing property in the early-stage immersion due to the swollen polyelectrolytes migrating to the scratched region and the calcium cations of the corrosive medium as an ionic crosslinker intercalated in the swollen polyelectrolytes forming calcium alginate and filling the micro-scale scratch. During the later-stage immersion, the self-healing coating showed excellent self-strengthening performance originating from the formation of the more and more compact film with calcium cations intercalated. This research provides an effective strategy to prolong the service life and improve corrosion performance for the implants in the human body environments.

Cobalt oxide nanosheets (Co3O4 NSs)/polypyrrole nanowire (PPy NW) core-shell nano-heterostructures based on nickel foam (NF) were fabricated for electrochemical non-enzymatic glucose determination. The Co3O4/PPy nanostructures grew directly on nickel foam substrate by electrochemical deposition processes. The PPy NW core and the Co3O4 NS shell constructed the hierarchical nanocomposites to form a three dimensional micro−nanostructure in the micropores of NF. The as-prepared Co3O4/PPy/NF heterostructures were characterized by using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The introduction of the Co3O4 NSs can provide a high surface area and lead to high sensitivity to glucose. Chronoamperometry was used to evaluate the sensitivity of the sensor toward glucose. Compared with NF, PPy/NF, and Co(OH)2/PPy/NF electrodes, the Co3O4/PPy/NF electrode exhibited higher electrocatalytic activity for the oxidation of glucose, and the proposed glucose sensor showed linear electrochemical responses to glucose with a low detection limit of 0.74 μM (S/N=3). In addition, the prepared biosensor revealed good selectivity in the presence of electro-active species such as d-fructose, uric acid, ascorbic acid and hydrogen peroxide, and provided an excellent platform for the determination of glucose in human urine samples.

In this work, Co3O4 nanosheets were fabricated on indium tin oxide (ITO) substrates by developing a simple electrochemical deposition and annealing method. The as-prepared Co3O4 nanosheets were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflection infrared (ATR-IR) spectroscopy and Raman spectroscopy. The Co3O4 nanosheets modified ITO electrode was used for the electrochemical analysis of various trace lead ions by differential pulse anodic stripping voltammetry. The electrode was found to be highly selective to Pb(II) in the range of 1–100 μg L−1, and exhibited a sensitive current response with a limit of detection (LOD) of 0.52 μg L−1. Furthermore, the developed electrochemical Pb(II) sensor exhibited a high stability and reproducibility with a simple regeneration process.

A simple and practical method was developed to prepare a series of phytic acid (PA)–metal complex coatings on iron substrate by directly immersing the iron samples in the mixed solutions containing PA and metal ions. The key technologies of fabricating PA–metal complex coatings include: (i) anchoring of PA molecules onto the iron surface via complexation with Fe2+ ions dissolved from the iron substrate, and (ii) layer-by-layer deposition of PA–metal complexes on the PA/Fe2+ bottom layer through the bridging effect of additive metal ions. The present method was applicable to the film-forming process of a variety of metal ions, such as Zn2+, Ca2+, Co2+ and Ni2+, and the as-prepared PA–metal complex coatings were defined as PA–M conversion coatings (M = Zn2+, Ca2+, Co2+ and Ni2+ herein). Due to the strong coordination ability, PA molecules may be self-assembled on the iron surface, forming a layer of organic thin film (here defined as PA film), without the help of additive metal ions. However, the comparison between PA film and PA–M coatings shows that PA–M coatings were much thicker (over 15 μm) and denser and also possessed much stronger anti-corrosion performance compared to the PA film. The present study provides a new path for the fabrication of environmentally-friendly PA-based chemical conversion coatings and further broadens the application range of PA in metal surface pretreatment.

The Fe-doping of hierarchical Co hydroxide nanosheet arrays (CoyFe1−y(OH)x NSAs) integrated on a three-dimensional electrode is shown to contribute to both increasing the available surface area and number of active sites. Ultrathin secondary nanosheets with different Co to Fe ratios that are subsequently grown on these primary nanoarrays are found to exhibit high oxygen evolution reaction (OER) activity. The optimal composition of CoyFe1−y(OH)x NSAs turns out to be Co0.7Fe0.3(OH)x NSAs, which allows for an OER onset overpotential as low as 220 mV and a small Tafel slope at 62.4 mV dec−1, while also providing excellent long-term durability (>100 h) and a high turnover frequency (TOF) of 0.172 s−1 at an overpotential of 380 mV. The specific activity of Fe-doped Co0.7Fe0.3(OH)x NSAs at an overpotential of 350 mV (0.37 mA cmBET−2) is also twice as high as that of undoped Co(OH)2 NSAs.

With the rapid development of rechargeable zinc ion (Zn-ion) batteries, it is essential to understand and modulate the energy storage process of the active component to maximize the battery performance. In this research, manganese oxide (MnO2) wrapped zinc hexacyanoferrate (ZnHCF) nanocubes (ZnHCF@MnO2) were prepared using an in situ co-precipitation method. The resulting composite with a unique structure was able to modulate the Zn-ion storage because of the incorporation of capacitive and intercalative properties of both components together with the redox reactions, benefiting from the synergistic effects. Thus, the encapsulation of ZnHCF nanocubes with MnO2 nanosheets gives a high discharge capability for Zn-ion storage with an operation voltage as high as ∼1.7 V. Impressively, the flexible quasi-solid-state Zn-ion battery was assembled using a neutral polymer gel electrolyte, and this resulted in a battery which had potential applications for specific wearable electronics.

Burgeoning interest in flexible and wearable electronics sparks the rapid development of flexible fiber-shape supercapacitors (SCs). Herein, three-dimensional porous reduced graphene oxide (RGO) aerogel is deposited on flexible Ni wire via a simple aqueous reduction method. RGO aerogel exhibits good capacitive performance, thanks to its unique porous structure and good electrical conductivity. In order to fabricate an asymmetric SC, nickel hydroxide nanosheets are controllably deposited on the RGO sheets as the positive electrode while the RGO aerogel coated Ni wire is used as negative one. The obtained flexible fiber SCs exhibit good performance with high power/energy densities (10.3 kW kg–1/3430 mW cm–3, 24.5 Wh kg–1/0.83 mWh cm–3) and good cycling stability (83% retention, even after 6000 cycles). The solid-state nature combined with good flexibility makes the fiber SCs attractive for energy storage applications in portable and wearable electronics. The interfacial deposition of reduced graphene oxide ...

The article describes an electrochemical sensor for the detection of uric acid (UA) by using a glassy carbon electrode (GCE) modified with a composite consisting of polytetraphenylporphyrin, polypyrrole, and graphene oxide. The PPy/GO nanocomposites were synthesized by in-situ chemical oxidation polymerization. Microspheres loaded with p-TPP were mixed into the PPy/GO nanocomposite, deposited on the GCE and dried upon which aggregation occurs. The nanocomposites were characterized by scanning electron microscopy, FTIR and Raman spectroscopy. The sensor was applied to the voltammetric determination of UA by differential pulse voltammetry (DPV). The oxidation current varies with the UA concentration in the range from 5 to 200 μM, and electrochemical response is distinctly improved compared to GCEs modified with p-TPP or PPy/GO only. The modified electrode shows excellent linearity, lower detection limit of 1.15 μM. The results also demonstrate that the modified electrode exhibited good selectivity and sensitivity toward UA even in the presence of AA and DA.

An electrochemical sensor was developed for detecting heavy metal ions by using a phytic acid functionalized polypyrrole (PPy)/graphene oxide (GO) modified electrode. PPy/GO nanocomposites were synthesized by in situ chemical oxidation polymerization. The PPy/GO nanocomposites were functionalized with phytic acid (PA) molecules by electrostatic attraction. The structural features of the fabricated nanocomposites were confirmed by transmission electron microscopy (TEM), attenuated total reflection infrared (ATR-IR) spectroscopy and Raman spectroscopy. The PA/PPy/GO modified electrode exhibited high electrochemical conductivity, and produced a remarkable increase in peak current compared with the PPy/GO and PA/GO modified electrodes. The developed sensor was used for the electrochemical analysis of various trace metal ions by differential pulse voltammetry (DPV). The modified electrode demonstrated to measure Cd(II) and Pb(II) with a linear working range of 5–150 μg/L. This work demonstrated a simple, rapid and high performing electrochemical strategy for high-sensitivity detection of heavy metal ions.

The rapid development of advanced energy-storage devices requires significant improvements of the electrode performance and a detailed understanding of the fundamental energy-storage processes. In this work, the self-assembly of two-dimensional manganese oxide nanosheets with various metal cations is introduced as a general and effective method for the incorporation of different guest cations and the formation of sandwich structures with tunable interlayer distances, leading to the formation of 3D Mx MnO2 (M=Li, Na, K, Co, and Mg) cathodes. For sodium and lithium storage, these electrode materials exhibited different capacities and cycling stabilities. The efficiency of the storage process is influenced not only by the interlayer spacing but also by the interaction between the host cations and shutter ions, confirming the crucial role of the cations. These results provide promising ideas for the rational design of advanced electrodes for Li and Na storage.

Rechargeable aqueous batteries are very attractive as a promising alternative energy storage system, although their reversible capacity is typically limited. A new rechargeable Na-Zn hybrid aqueous battery with nickel hexacyanoferrate (NiHCF) cathode and the nanostructured zinc anode is fabricated. The rational combination of two materials with mild aqueous electrolyte renders the devices with an average operating voltage close to 1.5 V, higher specific capacity of 76.2 mAh g−1, and a good cycling stability with 81% capacity retention for 1000 cycles. These remarkable features can provide guidance for the development of rechargeable batteries from the naturally abundant electrode materials with neutral aqueous electrolytes.

A sensitive, selective and reusable electrochemical biosensor for the determination of mercury ions (Hg(2+)) has been developed based on thymine (T) modified gold nanoparticles/reduced graphene oxide (AuNPs/rGO) nanocomposites. Graphene oxide (GO) was electrochemically reduced on a glassy carbon substrate. Subsequently, AuNPs were deposited onto the surface of rGO by cyclic voltammetry. For functionalization of the electrode, the carboxylic group of the thymine-1-acetic acid was covalently coupled with the amine group of the cysteamine which self-assembled onto AuNPs. The structural features of the T bases functionalized AuNPs/rGO electrode were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) spectroscopy. Each step of the modification process was characterized by cyclic voltammetry (CV) and electrochemical impedence spectroscopy (EIS). The T bases modified AuNPs/rGO electrode was applied to detect various trace metal ions by differential pulse voltammetry (DPV). The proposed biosensor was found to be highly sensitive to Hg(2+) in the range of 10 ng/L-1.0 µg/L. The biosensor afforded excellent selectivity for Hg(2+) against other heavy metal ions such as Zn(2+), Cd(2+), Pb(2+), Cu(2+), Ni(2+), and Co(2+). Furthermore, the developed sensor exhibited a high reusability through a simple washing. In addition, the prepared biosensor was successfully applied to assay Hg(2+) in real environmental samples.

The oxygen evolution reaction (OER) is a pivotal process for water-splitting and many other energy technologies involving oxygen electrodes. Herein, a new synthesis strategy is proposed to prepare OER catalysts based on a simple yet flexible in situ decomposition of Co-based acetate hydroxide metal-organic frameworks (MOFs). This process allows straightforward fabrication of various 2D hydroxide ultrathin nanosheets (UNSs) with excellent component controllability. The as-obtained Co-based hydroxide UNSs demonstrate superior catalytic activity for the OER due to the exposure of numerous active sites. In particular, the CoNi hydroxide UNSs exhibit low overpotentials (η) of 324 and 372 mV at current densities of 10 and 100 mA·cm–2, respectively; a large turnover frequency (TOF) of 0.16 s–1 at η = 380 mV; and a small Tafel slope of 33 mV·dec–1 in an alkaline environment. Importantly, these values are superior to those of the state-of-theart IrO2 commercial electrocatalyst. This facile strategy enables the exploration of more efficient and economic OER electrocatalysts with various constituents and opens a promising avenue for large-scale fabrication of functional nanocatalysts for use in clean energy technologies.

Ultra-small Fe3O4 nanocrystals (NCs)/garphene nanosheets (GNSs) composites have been synthesized through a facile gel-like film (GF) assisted method in this work. Fe3O4 NCs with particle size ∼10 nm homogeneously dispersed on 2D GNSs. Profiting from the ultra-small Fe3O4 NCs and GNSs, the composites demonstrate superior long-term and high-rate performance as anode materials for lithium ion batteries. Even at the current density of 5 A g−1, the reversible capacity still maintains 323.4 mAh g−1 after 700 cycles. This work might enlighten us on exploring preferable strategies to develop advanced metal oxides NCs/GNSs composites anode materials for lithium ion batteries or other energy storage devices.

Cobalt-based metal-organic framework (Co-MOF) and MOF-derived cobalt hydroxide (Co(OH)2) were successfully prepared by ionothermal and one-pot conversion methods, respectively. The introduction of ionic liquid in the synthesis of MOF could enhance electrical conductivity, thereby improving its electrocatalytic performance. The morphologies and structural compositions were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Cyclic voltammetry (CV) and amperometry investigation showed that the Co-MOF displayed higher electrochemical sensing performance toward glucose as compared to the Co(OH)2. The Co-MOF modified electrode offered a wide linear range (from 5 μM to 900 μM) and a low detection limit of 1.6 μM (S/N = 3). The electrochemical glucose sensor also exhibited excellent stability, reproducibility and selectivity. The MOFs impregnated with ionic liquids probably are capable of overcoming the disadvantage of the traditional MOFs, and the effective electrochemical property of the ionic liquid incorporated Co-MOF for the sensing of glucose can provide a direction for the bioactive molecules determination.

Aqueous batteries designed with K-ions have outstanding potential for future energy storage applications. When coupled with cathode and anode materials both operating with the intercalation mechanism, K-ion batteries could have kinetics and stability similar to Li-ion batteries in principle but with a much lower cost. However, the electrode materials developed so far still suffer from poor stability and limited activity, especially from the anode side. Herein, a new concept of symmetric K-ion batteries was developed by using potassium Prussian blue (KPB) as a bipolar material. The KPB particles were grown on flexible and strong wiper cloth substrates that were pre-coated with polypyrrole (PPy). The use of PPy as an interlayer not only boosted electrical conductivity but also ensured uniform growth of KPB particles. The synthesized KPB@PPy@wiper electrodes have superior flexibility and stability, and exhibited two redox pairs both with remarkable kinetics. When used as bipolar electrodes in combination with a gel solid-state electrolyte, they delivered a well-defined discharge voltage plateau at ∼0.6 V with superior rate capability and cycling stability. This work could provide new insights into the design of K-ion batteries, and give new options for developing flexible solid-state devices.

A signal amplification electrochemical aptasensor for ultrasensitive detection of lipopolysaccharide (LPS) was fabricated. The sensor was constructed with a probe of LPS aptamer and a copper ions-mediated gold nanoparticles aggregate (Cu/Au NA) as a signal amplification material. The Cu/Au NAs comprising copper ions (Cu2+) and L -cysteine modified AuNPs were fabricated by a self-assembly process. For functionalization of the electrode, the carboxylic group of a mercaptoacetic acid self-assembly layer was covalently coupled with the amine group of the aptamer. The aptamer with high specificity and affinity can effectively gather the dissociative LPS firstly, and the Cu/Au NAs were captured by anionic groups of the carbohydrate portions from LPS molecules based on the specific interactions. With the employment of the sandwich-type biosensor, the strategy can significantly amplify the electrochemical signal for determination of trace amount of LPS. The sensing performance of the electrochemical sensor was investigated by differential pulse voltammetry (DPV) and the stripping peak currents of Cu re-oxidized to Cu2+ was used to monitor the level of LPS. The electrochemical aptasensor exhibited excellent sensitivity toward LPS with a detection limit of 0.033 pg/mL (S/N = 3). The biosensor also exhibited a high specificity toward LPS in the presence of other common interfering substances and was easily regenerated. Furthermore, the fabricated biosensor showed a good practical application for LPS determination in human serum samples.

We demonstrated an interesting phenomenon that the electrochemical reduction of mercury ions (Hg2+) caused distinctly different morphology of gold nanorods (Au NRs) depending on the concentration of Hg2+. Specifically, in the case of low concentration, mercury formed through electrochemical reduction only deposited onto the gold surface, and then could be reversibly removed from the gold surface by electrochemical stripping process without causing obvious changes of Au NRs in shape and size. But in the case of high concentration, the reduced Hg not only deposited onto the gold surface but also entered into the interior of Au NRs making them change into gold nanospheres (Au NSs) in an irreversible manner due to the alloying effect of gold with Hg. In this situation, even though the most of Hg was removed, the Au NSs can no long return to the previous rod shape. The changing trend of Au NRs was characterized well by measuring the corresponding UV-Visible spectra. The formation of the Au/Hg nanoalloy was confirmed by high-resolution transmit electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) results. The present study is helpful for having better understanding of the mechanism of electrochemical mercury-analysis by Au nanoparticles, and necessary to optimize the Au nanoparticles-based Hg sensing strategies.

Facile interfacial growth of MnO2 nanoparticles on carbon nanofibers (MnO2/CNF) and the application of this material as a high-performance positive electrode material in asymmetric supercapacitors are presented. Rational combination of MnO2/CNF positive and CNF negative electrode materials enabled asymmetric devices with extended operating voltage windows of 1.8 V, and much higher power densities (4434 W kg−1) and energy densities (36 W h kg−1) compared with similar devices being reported. The assembled novel hybrid aqueous asymmetric capacitor shows excellent cycling stability with 90.9% capacity retention for 1000 cycles. The asymmetric supercapacitors were based on low cost and environmental friendly materials and have great potential for practical devices.

Sodium-based intercalation aqueous pseudocapacitive energy systems are attractive because of their obvious advantages including improved safety, low cost and environmental friendliness. Herein, an aqueous sodium-ion capacitor with the cobalt hexacyanoferrate (CoHCF) as the cathode electrode and carbon micro-spheres (CMS) as the anode electrode was fabricated, showing an extended operating voltage window (2 V), excellent capacitance behaviour, and high energy density (54.4 Wh kg −1 ). The present results provide meaningful clues to design new intercalation pseudocapacitor for future practical applications. And these remarkable features may pave the way to next-generation large-scale production of high performance hybrid supercapacitors performed as regulation or complementary devices.

Super-hydrophobic surfaces are usually prepared by manipulating the surface roughness and surface chemistry of various materials. Herein, we report two facile, environmentally friendly and inexpensive methods for the fabrication of super-hydrophobic (SH) coatings on cold rolled steel (CRS) and iron substrates using electrodeposition and etching to control surface roughness in combination with the self-assembly technique. By modifying the rough surfaces with stearic acid (SA) and hydrolysed octyltriethoxysilane (OTES), the water contact angles (WCA) of the super-hydrophobic ZnO coatings reaches up to 160° and the WCA of the super-hydrophobic coatings on etched iron is 155°. The mechanisms for the formation of the super-hydrophobic coatings fabricated by SA and OTES self-assembled thin films on rough steel and iron substrates are investigated by means of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS) results show that the SH coatings effectively protect the substrate metals from corrosion in 3.5% NaCl solution and increase the inhibition efficiency to approximately 93% and 86%, for the super-hydrophobic ZnO coating and super-hydrophobic silica coating on etched iron, respectively.