Nano-sized TiO 2 photocatalytic water-splitting technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the rapid recombination of photo-generated electron/hole pairs as well as backward reaction and the poor activation of TiO 2 by visible light. In response to these deficiencies, many investigators have been conducting research with an emphasis on effective remediation methods. Some investigators studied the effects of addition of sacrificial reagents and carbonate salts to prohibit rapid recombination of electron/hole pairs and backward reactions. Other research focused on the enhancement of photocatalysis by modification of TiO 2 by means of metal loading, metal ion doping, dye sensitization, composite semiconductor, anion doping and metal ion-implantation. This paper aims to review the up-to-date development of the above-mentioned technologies applied to TiO 2 photocatalytic hydrogen production. Based on the studies reported in the literature, metal ion-implantation and dye sensitization are very effective methods to extend the activating spectrum to the visible range. Therefore, they play an important role in the development of efficient photocatalytic hydrogen production.

A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production

1. Setting the Scope of the Challenge 6474 1.1. The Need for Solar Energy Supply and Storage 6474 1.2. An Imperative for Discovery Research 6477 1.3. Scope of Review 6478 2. Large-Scale Centralized Energy Storage 6478 2.1. Pumped Hydroelectric Energy Storage (PHES) 6479 2.2. Compressed Air Energy Storage (CAES) 6480 3. Smaller Scale Grid and Distributed Energy Storage 6481 3.1. Flywheel Energy Storage (FES) 6481 3.2. Superconducting Magnetic Energy Storage 6482 4. Chemical Energy Storage: Electrochemical 6482 4.1. Batteries 6482 4.1.1. Lead-Acid Batteries 6483 4.1.2. Alkaline Batteries 6484 4.1.3. Lithium-Ion Batteries 6484 4.1.4. High-Temperature Sodium Batteries 6484 4.1.5. Liquid Flow Batteries 6485 4.1.6. Metal-Air Batteries 6485 4.2. Capacitors 6485 5. Chemical Energy Storage: Solar Fuels 6486 5.1. Solar Fuels in Nature 6486 5.2. Artificial Photosynthesis and General Considerations of Water Splitting 6486

Solar Energy Supply and Storage for the Legacy and Nonlegacy Worlds

ZnS nanostructures: From synthesis to applications

The remarkable achievement by Fujishima and Honda (1972) in the photo-electrochemical water splitting results in the extensive use of TiO 2 nanomaterials for environmental purification and energy storage/conversion applications. Though there are many advantages for the TiO 2 compared to other semiconductor photocatalysts, its band gap of 3.2 eV restrains application to the UV-region of the electromagnetic spectrum ( λ  ≤ 387.5 nm). As a result, development of visible-light active titanium dioxide is one of the key challenges in the field of semiconductor photocatalysis. In this review, advances in the strategies for the visible light activation, origin of visible-light activity, and electronic structure of various visible-light active TiO 2 photocatalysts are discussed in detail. It has also been shown that if appropriate models are used, the theoretical insights can successfully be employed to develop novel catalysts to enhance the photocatalytic performance in the visible region. Recent developments in theory and experiments in visible-light induced water splitting, degradation of environmental pollutants, water and air purification and antibacterial applications are also reviewed. Various strategies to identify appropriate dopants for improved visible-light absorption and electron–hole separation to enhance the photocatalytic activity are discussed in detail, and a number of recommendations are also presented.

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Visible-light activation of TiO2 photocatalysts: Advances in theory and experiments

Environmental problems associated with organic pollutants and toxic water pollutants provide the impetus for sustained fundamental and applied research in the area of environmental remediation. Semiconductor photocatalysis offers the potential for complete elimination of toxic chemicals through its efficiency and potentially broad applicability. [1] Various new compounds and materials for photocatalysis have been synthesized in the past few decades. A successful example is TiO2, a metal oxide often used as a catalyst in photochemistry, electrochemistry, environmental protection, and in the battery industry. [2] Recently, transition-metal sulfides, in particular ZnS and CdS, have been intensively studied because of their unique catalytic functions compared to those of TiO2. [2, 3] These studies have revealed that ZnS nanocrystals (NCs) are good photocatalysts as a result of the rapid generation of electron– hole pairs by photoexcitation and the highly negative reduction potentials of excited electrons. The photocatalytic properties occur not only in the photoreductive production of H2 from water and the photoreduction of CO2, [4] but also in the phototransformation of various organic substrates such as the oxidative formation of carbon–carbon bonds from organic electron donors, cis–trans photoisomerization of alkenes, and the photoreduction of aldehydes and their derivatives. [5] The notable finding in nonmetalized ZnS photocatalysis is an irreversible two-electron-transfer photoreduction of organic substrates. [6] A favorable shift of the optical response into the visible region occurs subsequent to the doping of transition metal or rare-earth metal ions, such as Ni 2+ and Cu 2+ ; therefore, ZnS NCs can also be used as effective catalysts for photocatalytic evolution of H2 and photoreduction of toxic ions under visible-light irradiation. [7] An important application of ZnS is as a photocatalyst in environmental protection through the removal of organic

Mass Production and High Photocatalytic Activity of ZnS Nanoporous Nanoparticles

Metallophthalocyanine Based Conducting Electroactive Electropolymers and Their Applications As Electrochemical Pesticide Sensors

Bu calismada, yeni peripheral 1,2,4-triazol substitue metalsiz 4 , Zn(II) 5 , Ti(IV) 6, Ni(II) 7 ve Co(II) 8 ftalosiyanin turevlerinin sentezi, elektrokimyasal ve spektroelektrokimyasal ozellikleri rapor edilmistir. Komplekslerin voltametrik ve in situ spektroelektrokimyasal karakterizasyonu cozelti icinde gerceklestirildi. Nikel ve cinko ftalosiyaninler karakteristik olarak ortak “enerji araligi”,” pikten pike potansiyel ayrimlar” ve “yarim dalga pik potansiyel degerleri” ile ftalosiyanin halka bazli elektron transfer reaksiyonu verirken, kobalt ve titanyum ftalosiyanin komplekslerinin kavitesinde bulunan Co II ve Ti IV O metal iyonlari redoks aktif katyon olarak davranmistir. Kobalt ftalosiyanin indirgenme reaksiyonunda bir elektron [Co II Pc -2 ]/ [Co I Pc -2 ] -1 verirken, titanyum ftalosiyanin Pc ligand indirgenme islemine ek olarak, iki tane metal bazli indirgenme reaksiyonu [Ti IV OPc -2 ]/[Ti III OPc -2 ] -1 ve [Ti III OPc -2 ] -1 /[Ti III OPc -2 ] -2 gostermistir. Elektron transfer reaksiyonlari komplekslerin spektrumlarini oldukca degistirmistir. Bu durum komplekslerin ozellikle goruntuleme teknolojisinde pratik uygulamalarda en onemli beklentidir. Kobalt ve titanyum komplekslerinin redoks ve spektral yanitlari elektrolitte var olan molekuler oksijen tarafindan etkilenmistir. Bu da komplekslerin molekuler oksijene karsi elektrokatalitik ve elektosensor aktivitesini gostermektedir.

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Peripherally tetra 1,2,4-triazol substituted novel phthalocyanines: Synthesis, characterization, electrochemical and spectroelectrochemical properties

Synthesis, electrochemistry, and electrocatalytic activity of thiazole-substituted phthalocyanine complexes

A series of metal-free and metallo phthalocyanines (MPc) peripherally substituted with tetra-4-carboxyethylenephenoxy (M = 2H+ (H2Pc), Co2+ (CoPc), Zn2+ (ZnPc), and TiO2+ (TiOPc)) are used as dyes in the dye-sensitized solar cells (DSSCs). To predict the feasibility of MPcs as photosensitizers, electrochemical and in-situ spectroelectrochemical characterizations are first carried out since their redox mechanisms and optical responses under electrochemical excitations are the key factor for the requirement of the photosensitizers in DSSCs. The redox activities and opto-electrochemical responses of the compounds make them promising dye candidates with electrochemically reversible and multi-electron electron transfer reactions and suitable HOMO-LUMO band positions. The DSSCs using TiO2 film modified with these MPcs are developed and characterized. DSSC analyses indicate that especially H2Pc and TiOPc among the MPcs illustrate better photovoltaic performances than the others. The increase in efficiency of DSSC consisting of H2Pc and TiOPc is mainly associated with their suitable band positions and high electron lifetimes. When compared with the Pc bearing various substituents, ethylenephenoxy linkers between the Pc ring and the carboxyl anchoring groups significantly enhance the push-pull features between the dyes and TiO2 semiconductor, which results in 1.15, 2.98, 3.17 and 3.97 % power conversion efficiencies with CoPc, ZnPc, H2Pc, and TiOPc based DSSCs respectively. 

Electrochemical and spectroelectrochemical characterizations of phthalocyanines bearing peripherally tetra-4- carboxyethylenephenoxy anchoring groups and usage as photosensitizers of dye-sensitized solar cell

Atıf Koca

Papers

Metallophthalocyanine Based Conducting Electroactive Electropolymers and Their Applications As Electrochemical Pesticide Sensors

Peripherally tetra 1,2,4-triazol substituted novel phthalocyanines: Synthesis, characterization, electrochemical and spectroelectrochemical properties

Synthesis, electrochemistry, and electrocatalytic activity of thiazole-substituted phthalocyanine complexes

Electrochemical and spectroelectrochemical characterizations of phthalocyanines bearing peripherally tetra-4- carboxyethylenephenoxy anchoring groups and usage as photosensitizers of dye-sensitized solar cell

In Situ Electrochemical and Spectroelectrochemical Determination of Nitrogene and Halogene (Cl/Br) Atoms Substituted Novel Naphthoquinones (Nq’S)