Palladium and platinum are of well known value for applications in catalysis, hydrogen storage, and electrochemistry (Lewis, F. A., International Journal of Hydrogen Energy, 1996, v.21(6): pp. 461-464). Interfacial interactions can often limit performance so a high surface area material is usually desired. In these cases, as a practical maximum, every point in the material particle would be ideally within a few atoms of an interface. Such materials would exhibit high double-layer capacitance, higher reaction rates in kinetically limited interfacial reactions, and in the case of palladium, rapid charging with hydrogen. When the hydrogen isotope is tritium, the helium decay product is more likely to diffuse out of the particle, limiting the formation of bubbles that can compromise mechanical properties. Porous platinum and palladium thin films have been fabricated by electrochemical deposition in a surfactant template (cf. Attard, G. S.; Bartlett, P. N.; Coleman, N. R. B.; Elliott, J. M.; Owen, J. R.; Wang, J. H. Science 1997, v.278: pp. 838; Bartlett, P. N.; Gollas, B.; Guerin, S.; Marwan, J. Physical Chemistry Chemical Physics, 2002, v.4: pp. 3835; Choi, K. S.; McFarland, E. W.; Stucky, G. D. Advanced Materials, 2003, v.15: pp. 2018; Denuault, G.; Milhano, C.; Pletcher, D. Physical Chemistry Chemical Physics, 2005, v.7: pp. 3545; Elliott, J. M.; Attard, G. S.; Bartlett, P. N.; Coleman, N. R. B.; Merckel, D. A. S.; Owen, J. R. Chemistry of Materials, 1999, v.11: pp. 3602; Elliott, J. M.; Owen, J. R., Physical Chemistry Chemical Physics, 2000, v.2: pp. 5653), and films of porous nickel (the remaining Group 10 metal) have been formed by electrodeposition followed by dealloying (cf. Sun, L.; Chien, C. L.; Searson, P. C. Chemistry of Materials, 2004, v.16: pp. 3125). Furthermore, bulk powders of porous nickel can be formed conveniently through chemical reduction of nickel salts around a surfactant template (cf. Yamauchi, Y.; Yokoshima, T.; Momma, T.; Osaka, T.; Kuroda, K. Journal of Materials Chemistry, 2004, v.14: pp. 2935; Yamauchi, Y.; Momma, T.; Yokoshima, T.; Kuroda, K.; Osaka, T., Journal of Materials Chemistry, 2005, v.15: pp 1987; Yamauchi, Y.; Yokoshima, T.; Momma, T.; Osaka, T.; Kuroda, K., Electrochemical and Solid State Letters, 2005, v.8: pp. C141) and bulk platinum and palladium nanostructures have been achieved by radiolytic (cf. Surendran, G.; Ramos, L.; Pansu, B.; Prouzet, E.; Beaunier, P.; Audonnet, F.; Remita, H., Chemistry of Materials, 2007, v.19: pp. 5045) and chemical metal reduction in soft templates (cf. Kijima, T.; Yoshimura, T.; Uota, M.; Ikeda, T.; Fujikawa, D.; Mouri, S.; Uoyama, S., Angewandte Chemie—International Edition, 2004, v.43: pp. 228; Solla-Gullon, J.; Montiel, V.; Aldaz, A.; Clavilier, J. Journal of the Electrochemical Society, 2003, v.150, E104; Teng, X. W.; Liang, X. Y.; Maksimuk, S.; Yang, H. Small, 2006, v.2: pp. 249).
Other relevant methods include assembly of nanoparticles in a block copolymer (cf. Warren, S. C.; Messina, L. C.; Slaughter, L. S.; Kamperman, M.; Zhou, Q.; Gruner, S. M.; DiSalvo, F. J.; Wiesner, U., Science, 2008, v.320: pp. 1748) and reduction in mesoporous silica (cf. Shin, H. J.; Ko, C. H.; Ryoo, R. Journal of Materials Chemistry, 2001, v.11: pp. 260; Kang, H.; Jun, Y.; Park, J. I.; Lee, K. B.; Cheon, J., Chemistry of Materials. 2000, v.12: pp. 3530). These previous approaches have brought disadvantages in scalability, safety, purity, versatility, and/or pore density.
We present a convenient pathway that is satisfactory in all of these criteria, resulting in Pd and Pt nanopowders with 2 nm-3 nm pores that we have produced in gram-scale batches.