Hiroki Habazaki

Hokkaido University | Hokudai · Faculty of Engineering

The preparation of porous carbon from biomass flour as high-performance electrocatalysts for oxygen reduction reaction (ORR) was reported in this paper. The fast and vigorous pyrolysis of flour was induced in the presence of magnesium nitrate, by which MgO nanoparticles were introduced as nano-template to create numerous nanopores and to increase t...

Rechargeable aqueous zinc (Zn)‐ion batteries (RAZIBs), which use non‐flammable aqueous electrolytes and low‐cost electrode materials, show great potential to boost the development of safe, cost‐effective, and highly efficient energy storage systems. The adoption of lightweight and inexpensive aluminum (Al) as current collectors seems to be a good v...

Oxyhydrides have excellent potential as electrochemical and catalytic materials owing to the synergistic effects of the conductivity and redox activity of the hydride (H-) ion. However, harsh preparation conditions and their pyrolytic nature limit their applications. Herein, we discover highly durable oxyhydride perovskite BaZr0.5In(II)0.5O2.25H0.5...

Introduction Rechargeable aqueous zinc-ion batteries (RAZIBs) have some inherent advantages such as intrinsic safety, low-cost and theoretically high energy density, making them a current topic of interest. The problem is, dendritic growth of zinc (Zn) metal during electrodeposition occurs whatever alkaline electrolyte or neutral electrolyte, which...

This study investigates the oxygen evolution reaction (OER) activity of the FeNiCo alloy anodized at several temperatures in a fluoride-containing ethylene glycol electrolyte. When the alloy is anodized at 10 V, the OER activity in KOH electrolyte is highly enhanced on the alloy anodized at 15 and 20°C, at which non-uniform film growth proceeds. Th...

Towards the development of active and robust electrocatalysts for the oxygen evolution reaction (OER) to realize water splitting and CO2 electroreduction by renewable energies under practical conditions, brownmillerite-type composite oxide Ca2Fe2−xCoxO5 was synthesized by a sol–gel method and examined for the OER under neutral conditions. A pure br...

Hydration treatment of aluminum in hot water is important for its corrosion protection, and also this treatment is a crucial pretreatment in forming dielectric crystalline alumina films on the aluminum anode in aluminum electrolytic capacitors. In this study, a two-layer hydrated film formed on high purity aluminum by hot water treatment was examin...

Proton-conducting solid oxide electrolysis cells (H-SOEC) containing a 15-μm-thick BaZr0.6Ce0.2Y0.2O3-δ (BZCY622) electrolyte thin film, porous cathode cermet support, and La0.6Sr0.4Co0.2Fe0.8O3-δ anodes were fabricated using a reactive cofiring process at approximately 1400 °C. Steam electrolysis was conducted by supplying wet air to the anode at...

Rechargeable aqueous zinc (Zn) batteries have attracted great interests because of its inherent safety and cost-effectiveness. However, the uncontrollable Zn dendrite formation in aqueous electrolyte restricts its reversibility for long-life application. The bulge or passivation layer in pristine Zn surface serves as nuclei for large amount of Zn c...

Rechargeable aqueous zinc-ion batteries (RAZIBs) have some inherent advantages such as intrinsic safety, low-cost and theoretically high energy density, making them a current topic of interest. However, the phenomenon of...

This study revealed excellent corrosion resistance of the highly graphitized platelet-type carbon nanofibers due to hydroxyl passivation of the carbon edge plane.

Protonic solid oxide electrolysis cells (P-SOECs) are one of the most efficient devices for hydrogen production from renewable electricity, but a lack of suitable anodes has led to serious concerns...

Among several types of low‐temperature solid oxide fuel cells, hydrogen‐permeable metal‐supported fuel cells (HMFCs) are devices that can achieve outputs of approximately 1.0 W cm−2 at 400 °C. This work clarifies the mechanism for promoting the cathode reaction on proton‐conducting ceramics at such low temperatures. Combined numerical and electroch...

Because of the limited availability of fossil fuels and pertinent global environmental issues, hydrogen production via electrochemical water splitting using renewable resources is an important alternative for future energy economies. For efficient alkaline water electrolysis to produce hydrogen, we need to develop highly active and durable electroc...

Protonic solid oxide steam electrolysis cells (P-SOECs) based on BaZrxCe0.8xYb0.1Y0.1O3−δ proton conductors are promising to produce “green” hydrogen from renewable energy at intermediate temperatures. Herein, we demonstrate that the electrolysis performances of a cell with a high-Zr-content electrolyte, BaZr0.6Ce0.2Y0.1Yb0.1O3−δ (BZCYYb6211), can...

The reaction pathway of the oxygen reduction reaction (ORR) is strongly affected by the electrolytic environment. Meanwhile, the ORR mechanism on transition-metal oxide catalysts has not been studied intensely in very concentrated alkaline solutions that are used in practical metal-air batteries. Herein, we report the in situ activation of ORR cata...

Latent heat storage using metals as solid-liquid phase change materials (PCMs) have been concerned for medium-temperature thermal energy storage. However, due to the leakage and corrosion problems during phase transformation, the use of metallic PCMs are greatly limited. Encapsulation of PCM microparticles to form microencapsulated PCMs (MEPCMs) is...

On the way to achieve practical lithium (Li) metal anode for next-generation batteries, the formation and accumulation of inactive “Dead Li” is an unavoidable issue. The accumulation of “Dead Li”...

Although insertion of a thin insulating layer between metal electrodes and a semiconducting channel is an effective way to improve device performance, the exact reason for improvement in performance has not been elucidated. In this study, we systematically investigated the role of an Al2O3 interlayer sandwiched between Al metal electrodes and an am...

A simple anodizing technique has been employed to develop highly active electrocatalysts that can be applied to the oxygen evolution reaction (OER) in alkaline media. NiFe alloys were electrodeposited and anodized to form a porous electrocatalytic layer. This approach produces highly active electrodes without the need for noble metals, binders, or...

1. Introduction Lithium (Li) metal is regarded as the ideal anode for lithium batteries due to its ultra-high theoretical specific capacity (3860 mAh g ⁻¹ ), low density (0.59 g cm ⁻³ ) and lowest negative electrochemical potential (-3.04 V vs. Standard Hydrogen Electrode). ⁽¹⁾ However, caused by several remaining hurdles, including i) the thermody...

Zinc-air secondary battery (ZAB) is a promising candidate for the development of new generation of energy conversion systems due to its relatively high theoretical energy density of 1370 Wh kg ⁻¹ . The decrease of overpotential for oxygen-reduction-reaction (ORR) and oxygen-evolution-reaction (OER) in air electrode, together with providing of high...

A solid oxide steam electrolysis cell (SOEC) has attracted much attention for the production of a clean H 2 from water by using renewable electricity. Activation energy of proton conduction in proton conducting perovskite oxides BaZr x Ce 1- x-y Y y O 3-δ (BZCY) is much lower than that of yttria stabilized zirconia which is practically used for the...

Protonic ceramic cells (PCCs), including fuel cells and electrolysis cells, are based on protonic conducting Ba(Zr, Ce)O 3 electrolytes, and have more advantages at operating temperatures below 600 °C than solid oxide cells (SOCs) based on a oxide ion conducting Y-ZrO 2 because the activation energy required for proton conduction (0.3–0.6 eV) is lo...

Hydration treatment of aluminum is often used for corrosion protection of aluminum alloys and for the formation of dielectric alumina layer in aluminum electrolytic capacitors. Hydrated alumina layer is usually formed by immersing aluminum with and without a porous anodic alumina layer in hot water. The hydrated alumina layer plays an important rol...

Protonic ceramic fuel cells (PCFCs) have been drawing considerable attentions because of their potential for high-power operating at intermediate temperature (IT), 400–600°C, which is a salient issue for their practical implementation. BaZr 0.1 Ce 0.7 Y 0.2 O 3 , popular proton-conducting ceramic electrolyte material, has notably high conductivity...

In this study, zinc is anodized at different voltages in 0.1 mol·dm−3 KOH electrolyte to form nanoporous anodic films. Dark-colored anodic films are formed at anodizing voltages ≤ 6 V, whereas colorless anodic films are developed at voltages ≥ 7 V. The anodic films formed at all voltages consist of crystalline ZnO, which was identified by X-ray dif...

Anodizing of iron (100), (110) and (111) single crystals in mono-ethylene-glycol electrolyte containing 1.5 mol dm−3 water and 0.1 mol dm−3 ammonium fluoride leads to formation of anodic iron nanopores/nanotubes where the nanopores are essentially composed of oxide nanotubes separated by iron fluoride matrix. It was found that electrochemical therm...

Development of highly active bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is required for air electrodes of zinc-air secondary batteries (ZAB). In this study, we synthesize spinel-type MnCo2O4 (MCO) nanoparticles on highly graphitized platelet-type carbon nanofibers (pCNF) via a solvothermal...

The effect of alloying sputter-deposited Ti with 2 at.% of Au on the growth of anodic nanotubes was studied in monoethylene glycol electrolyte containing 1.0 mol dm−3 of water and 0.1 mol dm−3 of ammonium fluoride. The classic shape of nanotubes modified with quasi-spherical clusters of Au48-198 was obtained on Ti-Au (2 at.%). The results were comp...

Copper is an important practical metal with a high thermal conductivity that is widely used as a heat exchanger material. However, a liquid film often forms on the Cu surface through water vapor condensation, causing a large resistance to heat transfer. To address this issue, a superhydrophobic Cu metal nanowire surface is developed herein via Cu a...

Slippery Surfaces In article number 1900836 by Tomohiro Inoue, Hiroki Habazaki and co‐workers, fluorine‐free slippery liquid‐infused porous surface (SLIPS) is prepared using hierarchically porous aluminum substrate and silicone lubricant. The F‐free SLIPS is more environmentally acceptable compared with the F‐containing SLIPS and exhibits highly re...

Brownmillerite-type Ca2FeCoO5 (CFCO) is a highly active electrocatalyst for the oxygen evolution reaction (OER). In this study, we identified the actual catalytically active phase of this oxide formed via the long-term OER and, moreover, demonstrated that the active phase can persist during the OER for four weeks without significant loss of electro...

It is challenging for materials chemists to develop efficient, cobalt-free cathode materials for solid oxide fuel cells mainly because of the resource scarcity. This study demonstrates that a cubic-type La0.7Sr0.3Mn0.7Ni0.3O3-δ (C-LSMN7373) perovskite is promising for intermediate-temperature protonic ceramic fuel cells (PCFCs) because of the suffi...

Wide band gap oxide materials with additional infrared (IR) photosensing have rarely been reported due to the lack of the IR-associated sub band gap absorption. In this work, we report that the insertion of a thin aluminum oxide (Al2O3) layer between the Al electrode and indium gallium zinc oxide (IGZO) channel, deposited by atomic layer deposition...

Hindered by dendrite growth, unceasing volume change and repeated regeneration of solid-state electrolyte interface, the practical application of lithium (Li) metal anode is still facing challenges from low Coulombic efficiency (CE), insufficient safety performance and poor cyclic stability. Current collector plays a key role in regulating Li depos...

Porous anodic alumina films formed by anodizing of aluminum in acid electrolytes have a highly ordered, nanopore channels, which have attracted increased attention as template for various nanomaterials. Utilizing this template, platelet-type carbon nanofibers (pCNFs) have been successfully prepared by simply heating a mixture of the template and po...

Anodizing is a high voltage electrochemical conversion process that forms barrier-type oxide layers or self-organized nanoporous/nanotubular structures. So far, alumina-like nanopores and titania-like nanotubes could be successfully synthesized on many valve metals and alloys. Recently, anodizing become possible for base metals such as polycrystall...

Highly durable air electrodes for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in highly alkaline media are necessary to catalyze reactions in metal-air secondary batteries. Carbon is able to provide electronic conductivity and co-catalyze reactions, however, is typically oxidized under high-potential conditions above 1.1...

Organic phase change materials (PCM, such as paraffin) are broadly used in thermal energy storage systems, especially for the efficient utilization of solar energy and industrial waste heat, whereas their low shape-stability and poor heat transfer performance have hindered the practical applications. In this work, we aim at producing high-performan...

The development of thermal conductive and porous supporting scaffolds is believed to solve the problems of poor shape-stability and low thermal conductivity of solid-liquid transition-type phase change materials (PCMs), which are promisingly used for solar thermal energy storage and management. In this paper, textile-structured carbon scaffolds wit...

Slippery liquid infused porous surfaces (SLIPS) have been receiving increased attention. Fluorinated compounds have been used to prepare the SLIPS, but because of bioaccumulation and ecological impact of perfluoalkyl building blocks, fluorine‐free SLIPS system is preferable for practical applications. In this study, SLIPS has been prepared from hie...

Protonic ceramic fuel cells (PCFCs) have limited application below 500○C owing to their high ohmic and polarization resistances. Hence, efforts are ongoing to develop advanced fuel cells based on semiconductor device science as well as material interfacial engineering. Here, we demonstrate that hydrogen-permeable metal-supported fuel cells (HMFCs)...

The utilization of a Li metal anode is necessary in the development of next generation high energy density Li batteries, which is still hindered by problems of dendrite growth, volume change and electrolyte depletion. To overcome these difficulties, the employment of 3D porous current collectors has been demonstrated to be an effective strategy. Ho...

Phase change materials (PCMs) have shown promising applications for thermal energy storage and management. With the purposes of solving the critical leakage problem and improving the thermal conductive property of paraffin PCM, composite PCMs as-supported by carbon fiber bundles were fabricated by a simple vacuum impregnation. The porous and honeyc...

The formation of crystalline anatase films having important applications such as photocatalysis, solar cells, electrochromic applications, and bio-implants requires time-consuming multiple processes including heat treatments. In this paper, ultra-rapid formation of a crystalline anatase film on a tin substrate is realized by a cathodic deposition m...

Mixed proton-electron conductors (MPECs) are indispensable for the efficient operation of proton conducting ceramic fuel cells and electrolyzer cells at intermediate temperatures (below 500 ○C), but robust guidelines for their material design are still missing. Here, this study firstly reports on the massive uptake of proton carriers in cubic perov...

Anodizing of metals and alloys is a simple electrochemical process to form various nano-structured oxide films, including self-ordered nanoporous and nanotubular films. Typical examples are nanoporous alumina films with honeycomb morphology and nanotubular array of anodic titanium oxide. Recently, several nanowire-type anodic films have been prepar...

Recharchable zinc-air-battery is considered as one of the possible candidates to replace conventional lithium ion battery. One of the requirements for effective battery operation is an oxygen evolution reaction (OER) which needs to be provided in highly alkaline electrolyte. The A2BB`O5 Brownmillerite-type Ca2FeCoO5 electrocatalyst having 57 Pbcm s...

Recharchable zinc-air-battery is considered as one of the possible candidates to replace conventional lithium ion battery. One of the requirements for effective battery operation is an oxygen evolution reaction (OER) which needs to be provided in highly alkaline electrolyte. The A2BB`O5 Brownmillerite-type Ca2FeCoO5 electrocatalyst having 57 Pbcm s...

In situ X-ray absorption spectroscopy (XAS) was applied to investigate the Sn adlayer on platinized (pl-) Pt electrode in deaerated 0.2 M HClO4 solution containing 10⁻³ M Sn²⁺ in relation to the effect of Sn addition on electrocatalysis of Pt. A periodical emersion method under potentiostatic polarization, using pl-Pt plate (roughness factor Sr = 7...

Herein, high-valence-state Mn(V) oxide, barium manganate(V) (Ba3(MnO4)2), was examined as an anode electrocatalyst of a H⁺-conducting solid oxide steam electrolysis cell (H-SOEC). Ba3(MnO4)2 comprises C3v-symmetric MnO4³⁻ oxo-anions with three Mn-O single bonds and one Mn=O double bond because a lone pair of Mn⁵⁺ cation in d² configuration tends to...

Biomass-derived porous carbons with very high specific surface area (SSA) and heteroatom-doping are important for obtaining high performance supercapacitor. In this study, we report a simple and straightforward strategy, which involves the efficient and exothermic pyrolysis of Mg/K/Mg·K-nitrate-urea-cellulose mixture with subsequent high temperatur...

The practical use of organic phase change materials (PCMs) for solar thermal energy storage is limited by the leakage problem and the low thermal conductivity. As a good supporting and thermal conductive framework for organic PCM with shape-stability, three-dimensional carbon sponges are produced by the direct carbonization of low-cost and sustaina...

The effect of alloying of sputter-deposited Fe with 9 at.% tungsten on the growth of nanoporous anodic oxide was studied in ethylene glycol electrolyte containing 0.1 mol dm-3 ammonium fluoride and 1.5 mol dm-3 water. The classic nanoporous anodic film (Al2O3-like) was developed on pure Fe while the transition of nanopores to nanotubes (TiO2-like)...

In this work, high value-added N-doped hierarchical porous carbon (NHPC) for oxygen reduction reaction (ORR) electrocatalyst was prepared using biomass cellulose as the raw material. The pyrolysis of cellulose is accelerated by a redox combustion reaction of magnesium nitrate-carbohydrates (urea and cellulose) as-absorbed in cellulose fibers, which...

The wide application of organic phase change materials for thermal energy storage and management are limited by their low thermal conductivity and poor shape-stability. In this work, anisotropically thermal conductive and shape-stabilized phase change composites (PCCs) were successfully prepared with vertically aligned carbon fibers as supporting s...

In this study, platelet-type carbon nanofibers prepared by the liquid phase carbonization of polymers in the pores of a porous anodic alumina template were used to prepare the Co3O4/carbon electrocatalysts. For comparison, Co3O4 nanoparticles were also deposited on multiwall carbon nanotubes (MWCNTs). Both the nitrogen-free platelet-type carbon nan...

Stainless steels is practically important corrosion-resistant metallic materials, and additional surface functionalities including self-cleaning, anti-fouling, anti-ice and snow sticking and fluid drag reduction by the introduction of superhydrophobic and superoleophobic surfaces are of recent interest. Here, we report the micro-/nano-hierarchical...

The presence of alloying elements in aluminium alloys has a significant impact on the anodizing behaviour and results in the formation of porous anodic films with different chemical composition and morphology compared with those generated on pure aluminium. In this work, the effect of alloy element enrichment at the alloy/film interface and of cell...

Electrocatalytic activity for the 4e- transfer oxygen reduction reaction (ORR) was examined with perovskite-type La0.7Sr0.3Mn1-xNixO3-δ (x = 0-0.5) compounds in concentrated KOH. Electrochemical measurements by means of a rotating ring-disc electrode technique revealed that 10% substitution of Mn by Ni atoms significantly improved ORR activity wher...

Anodizing is a high voltage electrochemical conversion process that forms barrier-type oxide layers or self-organized nanoporous/nanotubular structures. So far, the Al 2 O 3 -like nanopores and TiO 2 -like nanotubes could be successfully synthesized on many valve metals and alloys. The proposed models of anodic oxide nanotubes growth, however, sacr...

This paper reports a survey of power generation characteristics of anode-supported thin film fuel cells with Zr-rich BaZrxCe0.8−xY0.2O3−δ (x = 0.4, 0.6, 0.7, and 0.8) proton-conducting electrolytes, which were fabricated by single step co-firing with Zn(NO3)2 additives at a relatively low temperature (1400 °C). The grain sizes significantly increas...

The growth of a uniform barrier-type anodic film on aluminum is usually terminated by electric breakdown, which is controlled by the resistance of electrolyte or anion concentration. In this study, highly resistive porous layers have been introduced by anodizing aluminum in sulfuric acid electrolyte followed by boiling water treatment to examine th...

This paper reports rapid self‐healing on superoleophobic hierarchically porous aluminum surfaces within 1 h even at room temperature. This self‐healing surface is prepared by infiltration of a liquid fluoroalkylsilane (FAS) coating into the substrate pores. The FAS‐infiltrated dual‐pore superoleophobic surface becomes superoleophilic after oxygen p...

Redox-based resistive switching memories (ReRAMs) are strongest candidates for the next generation nonvolatile memories. These devices are commonly composed metal/solid electrolyte/metal junctions, where the solid electrolyte is usually an oxide layer. A key aspect in the ReRAMs development is the solid electrolyte engineering, since it is crucial...

This paper reports unusual diffusion-controlled growth of TiO2 mesoporous anodic films on titanium in hot phosphate/glycerol electrolytes. The formation behavior was investigated by cyclic voltammetry (CV) between 0 and 5 V vs. Pt at 433 K. The current density became almost constant above 1.5 V vs. Pt during the positive potential sweep, and was ma...

Porous carbon has attracted great interest because of its distinctive structure and superior properties for designing electrochemical energy storage devices. In this work, we report a novel and facile method to fabricate nitrogen-doped porous carbon (NPC) with designed hierarchical multi-porous structure. The NPC is prepared using a facile and scal...