Nianbing Li

A one-step, cost-effective green method to in situ fabricate Ni(OH)2 hexagonal platelets on Ni foam as binder-free supercapacitor electrode materials

Nickel hydroxide (Ni(OH)2) is considered to be a promising alternative to the expensive and toxic RuO2 electrode material for high-performance supercapacitors; however, the fabrication method and electrochemical performance of suitable Ni(OH)2 structures are unsatisfactory. In the present work, a facile, cost-effective green method is developed to in situ fabricate Ni(OH)2 hexagonal platelets on Ni foam as a binder-free supercapacitor electrode with high performance. The Ni(OH)2 hexagonal platelets are self-grown on three-dimensional (3D) Ni foam by a one-step hydrothermal treatment of Ni foam in a 15 wt% H2O2 aqueous solution without the use of nickel salts, acids, bases, or post-treatments. The as-prepared Ni(OH)2 hexagonal platelets-Ni foam (HNF) electrode can be used directly as a supercapacitor electrode material, thereby avoiding the need for binders and conducting agents. The Ni(OH)2 hexagonal platelets demonstrate high capacitance (2534 F g−1 at a scan rate of 1 mV s−1) and excellent cycling stability (97% capacitance retention after 2000 cycles at a scan rate of 50 mV s−1). The fabrication method developed here has the significant advantage of low-cost, facile, green, and additive-free processing, and it is therefore a promising route for preparing self-supported metal (hydr)oxide electrodes for high-performance supercapacitors and other energy-storage devices.

Robust Biomimetic-Structural Superhydrophobic Surface on Aluminum Alloy

The following facile approach has been developed to prepare a biomimetic-structural superhydrophobic surface with high stabilities and strong resistances on 2024 Al alloy that are robust to harsh environments. First, a simple hydrothermal treatment in a La(NO3)3 aqueous solution was used to fabricate ginkgo-leaf like nanostructures, resulting in a superhydrophilic surface on 2024 Al. Then a low-surface-energy compound, dodecafluoroheptyl-propyl-trimethoxylsilane (Actyflon-G502), was used to modify the superhydrophilic 2024 Al, changing the surface character from superhydrophilicity to superhydrophobicity. The water contact angle (WCA) of such a superhydrophobic surface reaches up to 160°, demonstrating excellent superhydrophobicity. Moreover, the as-prepared superhydrophobic surface shows high stabilities in air-storage, chemical and thermal environments, and has strong resistances to UV irradiation, corrosion, and abrasion. The WCAs of such a surface almost remain unchanged (160°) after storage in air for 80 days, exposure in 250 °C atmosphere for 24 h, and being exposed under UV irradiation for 24 h, are more than 144° whether in acidic or alkali medium, and are more than 150° after 48 h corrosion and after abrasion under 0.98 kPa for 1000 mm length. The remarkable durability of the as-prepared superhydrophobic surface can be attributed to its stable structure and composition, which are due to the existence of lanthanum (hydr)oxides in surface layer. The robustness of the as-prepared superhydrophobic surface to harsh environments will open their much wider applications. The fabricating approach for such robust superhydrophobic surface can be easily extended to other metals and alloys.

Intelligent sponge with reversibly tunable super-wettability: robust for effective oil–water separation as both the absorber and filter tolerate fouling and harsh environments

We fabricate an intelligent and robust sponge by a one-step and low-cost ultrasonic-assisted dip coating (UADC) method, which involves the modification of the commercial sponge with TiO2 nanoparticles and a low-surface-energy compound (octadecanoic acid). The as-prepared sponge shows intelligent reversibly tunable super-wettability and exhibits robustness for effective oil–water separation. It can act as both the absorber and filter for the highly efficient separation of oil–water mixtures under different super-wettability conditions. More importantly, it has remarkably high chemical stability, which can separate oil–water mixtures in the extremely high acidic and alkaline environments as well as the extremely high salt concentration of seawater (such as 10 M H2SO4 and NaOH, and saturated NaCl media). Meanwhile, the as-prepared sponge has excellent antifouling ability, which shows self-cleaning performance during multiple fouling cycles. These extraordinary properties suggest that the as-prepared sponge will be a promising candidate for large-scale oil–water separation.

Experimental and theoretical investigations of Michelia alba leaves extract as a green highly-effective corrosion inhibitor for different steel materials in acidic solution

The aqueous Michelia alba leaf extract (MALE) was first evaluated as an inhibitor to the corrosion of different steel materials (industrial pure iron, stainless steel and carbon steel) in hydrochloric acid. The adsorption and corrosion inhibition of MALE were investigated by potentiodynamic polarization, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and quantum chemical calculations. The results showed that MALE acted as a highly-efficient mixed-type inhibitor for all steels and increasing temperatures benefited its corrosion inhibition. The adsorption of MALE on steel surfaces obeyed a Langmuir adsorption isotherm. Quantum chemical calculation results provided reasonable theoretical explanation for the inhibition property of MALE.

Metal powder–pure water system for rational synthesis of metal oxide functional nanomaterials: a general, facile and green synthetic approach

Metal oxide (MO) nanomaterials have played a pivotal role in many fields. The general, facile and green approach for rational synthesis of MO nanomaterials is highly desirable. In this work, a simple approach via an ultrasonic-assisted preoxidation and a subsequent hydrothermal oxidation (UAPO–HO) of metal powders directly in pure water without using any other chemicals has been developed as a general synthetic route to prepare MO nanomaterials. Three representative MO nanomaterials (Mn3O4 nanorods, ZnO nanopellets, and Fe3O4 nanocubes) have been successfully synthesized by this UAPO–HO approach for the first time. The properties of the newly synthesized MO nanomaterials, such like Mn3O4 as an electrode material for supercapacitors, ZnO as an photocatalyst for degrading organic pollutants, and Fe3O4 as a magnetic catalyst for disposing antibiotics, are investigated, which demonstrate attractive performance in energy storage and environmental protection. The synthetic approach developed here has the significant advantages of being chemical-utility least, product-purity high, facile, green and mild, which offers a unique clue for synthesis of MO nanomaterials.

O-Vacancy-enriched NiO hexagonal platelets fabricated on Ni foam as a self-supported electrode for extraordinary pseudocapacitance

To enhance the capacitive property of NiO-based electrodes, O-vacancy-enriched NiO hexagonal platelets have been fabricated in situ on an Ni foam current collector by a facile hydrothermal treatment of Ni foam in a H2O2 aqueous solution and subsequent calcination in N2 atmosphere. Due to the self-grown nature and the abundant oxygen vacancies, the as-prepared self-supported NiO electrode showed extraordinary pseudocapacitance. The specific capacitance of the as-prepared NiO electroactive materials was 2495 F g−1 at a scan rate of 1 mV s−1 (∼97% of the theoretical value of NiO) and the capacitance retention was higher than 80% when the current density increased from 0.5 to 10 A g−1. DFT computational studies proved the vital role of oxygen vacancies in increasing the conductivity, electrochemical active sites and surface reactivity, which substantially account for the significantly high specific capacitance and rate capability. This study may further broaden the applications of NiO-based materials and boost the research on oxygen nonstoichiometry.