Dana C. Bookbinder

Bio: Dana C. Bookbinder is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Viologen & Bioelectrochemistry. The author has an hindex of 9, co-authored 9 publications receiving 839 citations.

Improvement of photoelectrochemical hydrogen generation by surface modification of p-type silicon semiconductor photocathodes

Abstract: The improvement of H/sub 2/ evolution from two different types of catalytic p-type photocathode surfaces has been examined. p-Type Si has been platinized by phtotelectrochemically plating Pt(0) onto the Si surface. Such a photocathode shows significant improvement (compared to naked p-type Si) for photochemical H/sub 2/ evolution with respect to output photovoltage, fill factor, and overall efficiency. Such photocathodes having an optimun amount of Pt(0) give a pH-dependent output voltage with respect to the H/sub 2/O/H/sub 2/ couple, but the dependence is not a simple 59-mV/pH dependence. No pH dependence would be expected if Pt(0) formed a Schottky barrier when plated onto p-type Si. A second kind of H/sub 2/ evolution catalyst has been confined to the surface of p-type Si. Polymeric quantities of an electroactive N,N'-dialkyl-4,4'-bipridinium reagent, (PQ/sup 2 +/.)/sub n/, have been confined to the surface. The Br/sup -/ counterions of the polymer are then exchanged by PtCl/sub 6//sup 2 -/. Photoreduction then yields Pt(0) dispersed in the polymer. Such a surface is again significantly improved compared to naked p-type Si with respect to H/sub 2/ evolution. A comparison of the naked p-Si, the simply platinized, and the (PQ/sup 2 +//sup ///sup +//sub n/.nPt(0))/sub surf./ system is mademore » and contrasted to the expected behavior of an external Schottky barrier photocell driving an electrolysis cell with a Pt cathode. Experiments with n-type MoS/sub 2/, n-type Si, Pt, Au, and W cathodes functionalized with the (PQ/sup 2 +//sup ///sup +/.)sub n/.nPt(0))/sub surf./ system compared to the same surface directly platinized confirm an important difference in the mechanism of H/sub 2/ evolution catalysis for the two surface catalyst systems. p-Type Si modified with optimum amounts of Pt(0) by direct platinization appears to give improved H/sub 2/ evolution efficiency by a mechanism where the Pt(0) serves as a catalyst that does not alter the interface energetics of the semiconductor.« less

Photoreduction at illuminated p-type semiconducting silicon photoelectrodes. Evidence for Fermi level pinning

Abstract: Studies of p- and n-type Si electrodes are reported which show that semiconducting Si electrode surfaces do not allow efficient H/sub 2/ evolution in the dark (n type) or upon illumination with band gap or greater energy light (p type). The key experiment is that N,N'-dimethyl-4,4'-bipyridinium (PQ/sup 2 +/) is reversibly reduced at n-type Si in aqueous media at a pH where H/sub 2/ should be evolved at nearly the same potential, but no H/sub 2/ evolution current is observable. The PQ/sup 2+/+/.system may be useful as an electron-transfer mediator, since PQ/sup +/.can be used to effect generation of H/sub 2/ from H/sub 2/O using a heterogeneous catalyst. The PQ/sup +/.can be produced in an uphill sense by illumination of p-type Si in aqueous solutions. Studies of p-type Si in nonaqueous solvents show that PQ/sup 2 +/, PQ/sup +/., Ru(bpy)/sub 3//sup 2 +/, Ru(bpy)/sub 3//sup +/, and Ru(bpy)/sub 3//sup 0/ are all reducible upon illumination of the p-type Si. Interestingly, each species can be photoreduced at a potential approx. 500 mV more positive than at a reversible electrode in the dark. This result reveals that a p-type Si-based photoelectrochemical cell based on PQ/sup 2+/+/., PQ/sup +/l/sup 0//, Ru(bpy)/sub 3//sup 2+/+/,more » Ru(bpy)/sub 3//sup +/0/, or Ru(bpy)/sub 3//sup 0/-/ would all yield a common output photovoltage, despite the fact that the formal potentials for these couples vary by more than the band gap (1.1 V) of the photocathode. These data support the notion that p-type Si exhibits Fermi level pinning under the conditions employed.Surface chemistry is shown to be able to effect changes in interface kinetics for electrodes exhibiting Fermi level pinning.« less

Electrochromic Polymers Covalently Anchored to Electrode Surfaces. Optical and Electrochemical Properties of a Viologen‐Based Polymer

Abstract: Fonctionnalisation d'electrodes de platine et d'oxyde d'etain par le polymere redox derive du dibromure de {N,N'-bis [(trimethoxysilyl)-3 propyl] bipyridinium-4,4}

Synthesis of N,N'-dialkyl-4'bipyridinium reagents

Abstract: A novel class of dialkyl and dialkyl-aromatic viologens (4,4'dipyridinium compounds) and their salts which may be polymerized and covalently bonded to electrodes for use in electronic display systems.

Synthesis and characterization of a photosensitive interface for hydrogen generation: Chemically modified p-type semiconducting silicon photocathodes.

Abstract: p-Si photocathodes functionalized first with an N,N′-dialkyl-4,4′-bipyridinium redox reagent, (PQ2+/+-)surf, and then with a Pt precursor, PtCl62-, give significant efficiency (up to 5%) for photoelectrochemical H2 generation with 632.8-nm light. Naked p-Si photocathodes give nearly zero efficiency, owing to poor H2 evolution kinetics that are improved by the (PQ2+/+-)surf/Pt modification. The mechanism of H2 evolution from p-Si/(PQ2+/+-)surf/Pt is first photoexcitation of electrons to the conduction band of Si followed by (PQ2+)surf → (PQ+-)surf reduction. The dispersion of Pt then catalyzes H2O reduction to give H2 and regeneration of (PQ2+)surf. The overall energy conversion efficiency rivals the best direct optical to chemical conversion systems reported to date.

Solar Water Splitting Cells

Abstract: Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2

Light-Driven Heterogeneous Reduction of Carbon Dioxide: Photocatalysts and Photoelectrodes

Abstract: Photocatalysts and Photoelectrodes James L. White,† Maor F. Baruch,† James E. Pander III,† Yuan Hu,† Ivy C. Fortmeyer,† James Eujin Park,† Tao Zhang,† Kuo Liao,† Jing Gu,‡ Yong Yan,‡ Travis W. Shaw,† Esta Abelev,† and Andrew B. Bocarsly*,† †Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States ‡Chemical and Materials Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States

Amorphous Molybdenum Sulfide Catalysts for Electrochemical Hydrogen Production: Insights into the Origin of their Catalytic Activity

Abstract: We present a scalable wet chemical synthesis for a catalytically active nanostructured amorphous molybdenum sulfide material. The catalyst film is one of the most active nonprecious metal materials for electrochemical hydrogen evolution, drawing 10 mA/cm2 at ∼200 mV overpotential. To identify the active phase of the material, we perform X-ray photoelectron spectroscopy after testing under a variety of conditions. As deposited, the catalyst resembles amorphous MoS3, but domains resembling MoS2 in composition and chemical state are created under reaction conditions and may contribute to this material’s high electrochemical activity. The activity scales with electrochemically active surface area, suggesting that the rough, nanostructured catalyst morphology also contributes substantially to the film’s high activity. Electrochemical stability tests indicate that the catalyst remains highly active throughout prolonged operation. The overpotential required to attain a current density of 10 mA/cm2 increases by o...

Photochemical and Photoelectrochemical Reduction of CO2

Abstract: The recent literature on photochemical and photoelectrochemical reductions of CO(2) is reviewed. The different methods of achieving light absorption, electron-hole separation, and electrochemical reduction of CO(2) are considered. Energy gap matching for reduction of CO(2) to different products, including CO, formic acid, and methanol, is used to identify the most promising systems. Different approaches to lowering overpotentials and achieving high chemical selectivities by employing catalysts are described and compared.

Photoelectrochemical cells for solar hydrogen production: current state of promising photoelectrodes, methods to improve their properties, and outlook

Abstract: Harnessing solar energy for the production of clean hydrogen fuels by a photoelectrochemical (PEC) cell represents a very attractive but challenging alternative This review focuses on recent developments of some promising photoelectrode materials, such as BiVO4, a-Fe2O3, TaON, and Ta3N5 for solar hydrogen production Some strategies have been developed to improve PEC performances of the photoelectrode materials, including: (i) doping for enhancing visible light absorption in the wide bandgap semiconductor or promoting charge transport in the narrow bandgap semiconductor, respectively; (ii) surface treatment for removing segregation phase or surface states; (iii) electrocatalysts for decreasing the overpotentials; (iv) morphology control for enhancing the light absorption and shortening transfer distance of minority carriers; (v) other methods, such as sensitization, passivating layer, and band structure engineering using heterojunction structures, and so on Photochemical durability of the photoelectrodes is also discussed, since any potential PEC technology must balance efficiency against cost and photochemical durability Photochemical durability may be amended by optimizing the photoelectrode, electrocatalyst, and electrolyte at the same time In addition, solar seawater splitting is briefly introduced because it has received attention recently Finally, trends in research in PEC cells for solar hydrogen production are detailed