Size- and support-dependency in the catalysis of gold

Rising atmospheric levels of carbon dioxide and the depletion of fossil fuel reserves raise serious concerns about the ensuing effects on the global climate and future energy supply. Utilizing the abundant solar energy to convert CO2 into fuels such as methane or methanol could address both problems simultaneously as well as provide a convenient means of energy storage. In this Review, current approaches for the heterogeneous photocatalytic reduction of CO2 on TiO2 and other metal oxide, oxynitride, sulfide, and phosphide semiconductors are presented. Research in this field is focused primarily on the development of novel nanostructured photocatalytic materials and on the investigation of the mechanism of the process, from light absorption through charge separation and transport to CO2 reduction pathways. The measures used to quantify the efficiency of the process are also discussed in detail.

Photocatalytic reduction of CO2 on TiO2 and other semiconductors.

Since the time of the industrial revolution, the atmospheric CO(2) concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO(2) emissions are necessary. Large emission point sources, such as fossil-fuel-based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO(2) from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less-energy-intensive separation technology. This Review describes the CO(2) adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic-inorganic hybrids, and metal-organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO(2) capacities as well as other important parameters such as adsorption-desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO(2) adsorbents and their critical properties that will ultimately affect their incorporation into large-scale separation processes is presented.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

The Interaction of Water with Solid Surfaces: Fundamental Aspects Revisited

The past several decades have seen a significant rise in atmospheric carbon dioxide levels resulting from the combustion of hydrocarbon fuels. A solar energy based technology to recycle carbon dioxide into readily transportable hydrocarbon fuel (i.e., a solar fuel) would help reduce atmospheric CO2 levels and partly fulfill energy demands within the present hydrocarbon based fuel infrastructure. We review the present status of carbon dioxide conversion techniques, with particular attention to a recently developed photocatalytic process to convert carbon dioxide and water vapor into hydrocarbon fuels using sunlight.

Toward Solar Fuels: Photocatalytic Conversion of Carbon Dioxide to Hydrocarbons

Formation of carbidic and graphite carbon from CO on polycrystalline cobalt

XPS Characterization of reduced LaCoO3 perovskite

Adsorption of CO2 on TiO2 and Pt/TiO2 studied by X-ray photoelectron spectroscopy and Augen electron spectroscopy

Study of methanol electrooxidation on RhSn oxide, PtSn oxide, and IrSn oxide in comparison with that on the Pt metals

Amorphous Ni–Ti and Ni–Zr alloys for their possible use in water electrolysis cathode materials were investigated. The hydrogen electrode reaction in 1 M NaOH (1 M= 1 mol dm−3) proceeds via the Volmer-Tafel reaction route with mixed rate-determining characteristics. The electrocatalytic activity is augmented significantly with a treatment of the alloy electrodes with aq HF. Thus, the exchange current density reaches 10−3A cm−2 (apparent) at 303 K. The activation energy values are 9.4, 5.5, and 6.1 kcal mol−1 (1 cal=4.184J) for the Volmer and Tafel step and the overall reaction, respectively. Surface analyses of the electrodes have indicated that such a high activity is caused by a stable porous Ni layer which is formed on the surface by the acid treatment. Such a porous Ni layer was not effectively formed if the alloys were in crystalline states.

Isamu Toyoshima

Papers

Formation of carbidic and graphite carbon from CO on polycrystalline cobalt

XPS Characterization of reduced LaCoO3 perovskite

Adsorption of CO2 on TiO2 and Pt/TiO2 studied by X-ray photoelectron spectroscopy and Augen electron spectroscopy

Study of methanol electrooxidation on RhSn oxide, PtSn oxide, and IrSn oxide in comparison with that on the Pt metals

Amorphous Ni-Ti and Ni-Zr alloys for water electrolysis cathode materials.