Bismuth vanadate (BiVO4) has a band structure that is well-suited for potential use as a photoanode in solar water splitting, but it suffers from poor electron-hole separation. Here, we demonstrate that a nanoporous morphology (specific surface area of 31.8 square meters per gram) effectively suppresses bulk carrier recombination without additional doping, manifesting an electron-hole separation yield of 0.90 at 1.23 volts (V) versus the reversible hydrogen electrode (RHE). We enhanced the propensity for surface-reaching holes to instigate water-splitting chemistry by serially applying two different oxygen evolution catalyst (OEC) layers, FeOOH and NiOOH, which reduces interface recombination at the BiVO4/OEC junction while creating a more favorable Helmholtz layer potential drop at the OEC/electrolyte junction. The resulting BiVO4/FeOOH/NiOOH photoanode achieves a photocurrent density of 2.73 milliamps per square centimenter at a potential as low as 0.6 V versus RHE.

https://science.sciencemag.org/content/sci/early/2014/02/12/science.1246913.full.pdf

Nanoporous BiVO4 Photoanodes with Dual-Layer Oxygen Evolution Catalysts for Solar Water Splitting

/pdf/the-surface-chemistry-of-amorphous-silica-zhuravlev-model-4kfs2lx66q.pdf

The surface chemistry of amorphous silica. Zhuravlev model

Nanosizing--oral formulation development and biopharmaceutical evaluation.

Publisher Summary It is noted that colloidal particles can be effectively transported through subsurface porous media under certain hydrogeochemical conditions. If present in large concentrations, mobile colloids can act as carriers for strongly sorbing contaminants and thereby provide an unretarded transport pathway for contaminants that are otherwise strongly retarded. This potential transport pathway can be considered in risk assessments of sites heavily contaminated with toxic chemicals, such as certain radionuclides, heavy metals, and hydrophobic organic compounds. The chapter reviews the current state of knowledge about the behavior of colloids in porous media and their role in contaminant transport. The chapter also identifies some important future research needs. Colloids are commonly defined as small particles or other entities with dimensions roughly between 1 nm and 1 μm. These size limits to dissolved molecules on one side and to larger suspended particles on the other side. Colloidal particles remain stable in suspension over long time periods, unless they coagulate to form larger aggregates or deposit onto surfaces of larger grains.

Mobile Subsurface Colloids and Their Role in Contaminant Transport

http://www.vliz.be/imisdocs/publications/228699.pdf

Discrete suspended particles of barite and the barium cycle in the open ocean

Sampling of powders sampling of dusty gases in gas streams sampling and sizing from the atmosphere - air technology, Atcor Net 2000, Bausch and Lomb, Beckman, Centre for Air Environmental Studies, Climet Series 7000, Coulter Model 550 contamination monitor, Dynac, Gardner, GCA Miniram, Insitec PCSV-P, Kratel Partoscope, Leitz Tyndalloscope, Met One particle counters, Pacific Scientific Hiac/Royco particle counting systems, particle measuring systems, RAC particle monitors, Rotheroe and Mitchell digital dust indicator, Saab photometer, Sartorius, Sinclair Particle size, shape and distribution - shape regeneration by Fourier analysis, the Rosinn-Rammler distribution, mean particle sizes and specific surface evaluation for Rosinn-Rammler distribution Sieving microscopy interaction between particles and fluids in a gravitational field dispersion of powders incremental methods of particle size determination cumulative methods of sedimentation size analysis fluid classification - the Warmain cyclosizer, the Humboldt particle size analyzer TDS, the cross-flow elbow classifier, the Bahco classifier, the BCURA centrifugal elutriator, Analysette 9, the Donaldson classifier, the Micromeritics classifier Centrifugal methods - early instruments - the Marshall centrifuge and the MSA particle size analyser, the Alpine sedimentation centrifuge, the Mikropul Sedimentputer, the LADAL X-ray centrifuge, the LADAL pipette withdrawal centrifuge The electrical sensing zone method of particle size distribution determination (the Coulter principle) radiation scattering methods of particle size determination high-order Tyndall spectr (HOTS) permeametry and gas diffusion - alternative derivation of Kozeny's equation using equivalent capillaries Gas adsorption - BET isotherm for multilayer adsorption, comparison between BET and HJr methods, the Frenkel-Halsey-Hill equation (FHH), the Dubinin-Radushkevich equation (D-R), Kiselev's equation Other methods for determining surface area - Langmuir trough, Gravimetric method, the Rayleigh interferometer Determination of pore size distribution by gas adsorption - the Kelvin equation On-line particle analysis - Brinkmann analyser, Climet particle counting systems, Flowvision, Hiac/Royco (Pacific Scientific) particle counters, Horiba particle size analysers, the Insitic particle counter, Kane May particle size analysers, Kratel Partascope, Lasentec, Talbot optical-electronic method, the Erdco acoustical counter, the Coulter on-line monitor screening - the Cyclosensor, non-Newtonian rheological properties Appendix 1 Equipment and suppliers, manufacturers' and suppliers' addresses

Terence Allen

Papers

Particle Size Measurement