Disclosed are porous multi-metal oxide nanotubes and a production method therefor. In one aspect, methods for producing porous multi-metal oxide nanotubes are provided comprising: (a) preparing an admixture comprising metal-acetylacetonate precursors, polyacrylonitrile (PAN) and a solvent component; and (b) producing a nanocomposite from the admixture, wherein metals of the metal-acetylacetonate precursors comprise a non-radioactive alkali metal stable isotope and a non-radioactive alkaline earth metal stable isotope. As such, porous multi-metal oxide nanotubes having a single-phase multivalence may be obtained in high yield without using harmful chemical substances. In addition, the polymer electrolyte membrane including the porous multi-metal oxide nanotubes may have maintained and improved mechanical strength, and thus may have maintained durability even during cell operation and may also have improved proton conductivity even at low humidity. The fuel cell including the polymer electrolyte membrane may have improved performance.

Disclosed are porous multi-metal oxide nanotubes and a production method therefor. In one aspect, methods for producing porous multi-metal oxide nanotubes are provided comprising: (a) preparing an admixture comprising metal-acetylacetonate precursors, polyacrylonitrile (PAN) and a solvent component; and (b) producing a nanocomposite from the admixture, wherein metals of the metal-acetylacetonate precursors comprise a non-radioactive alkali metal stable isotope and a non-radioactive alkaline earth metal stable isotope. As such, porous multi-metal oxide nanotubes having a single-phase multivalence may be obtained in high yield without using harmful chemical substances. In addition, the polymer electrolyte membrane including the porous multi-metal oxide nanotubes may have maintained and improved mechanical strength, and thus may have maintained durability even during cell operation and may also have improved proton conductivity even at low humidity. The fuel cell including the polymer electrolyte membrane may have improved performance.

Disclosed herein are methods of forming substantially crystalline, dense silicon carbide fibers from infusible polysilazane fibers by utilizing a single stage pyrolysis. The pyrolysis is performed using a continuous process in a single furnace with a constant atmospheric condition. Also disclosed are substantially crystalline, dense silicon carbide fibers formed by these methods.

Disclosed herein are methods of forming substantially crystalline, dense silicon carbide fibers from infusible polysilazane fibers by utilizing a single stage pyrolysis. The pyrolysis is performed using a continuous process in a single furnace with a constant atmospheric condition. Also disclosed are substantially crystalline, dense silicon carbide fibers formed by these methods.

A polymer including, as the main chain, a metal-oxygen-metal bond including a structural unit represented by the following general formula (1): wherein M represents a metal atom selected from the group consisting of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, and Bi; R.sup.1 is selected from a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.1-C.sub.8 alkylcarbonyl group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, a (R.sup.5.sub.3Si-group, a (R.sup.6R.sup.7N) group, a 4-oxopent-2-en-2-yl group, a C.sub.5-C.sub.12 4-alkoxy-4-oxobuta-2-en-2-yl group, and a C.sub.10-C.sub.16 4-aryloxy-4-oxobuta-2-en-2-yl group; R.sup.2 and R.sup.3 are each independently a hydrogen atom or a C.sub.1-C.sub.8 alkyl group; R.sup.4 is a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, or a C.sub.1-C.sub.8 alkylcarbonyl group; R.sup.5 is a hydroxy group, a C.sub.1-C.sub.8 alkyl group, a C.sub.5-C.sub.12 alicyclic alkyl group, a C.sub.1-C.sub.12 alkoxy group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, or a group having a siloxane bond; a plurality of R.sup.5 may be the same or different; R.sup.6 and R.sup.7 are each independently a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.5-C.sub.12 alicyclic alkyl group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, or a C.sub.1-C.sub.12 acyl group; R.sup.6 and R.sup.7 may be linked via a carbon-carbon saturated bond or a carbon-carbon unsaturated bond to form a ring structure; m is an integer that represents the valence of the metal atom M; a is an integer of 1 to (m?2); and b is an integer of 1 to 6, and c is an integer of 1 to 5. Provided is a polymer including a metal-oxygen-metal bond as the main chain that is stably present without aggregating or turning into a gel even in high concentration and high viscosity.

##STR00001##

A polymer including, as the main chain, a metal-oxygen-metal bond including a structural unit represented by the following general formula (1): wherein M represents a metal atom selected from the group consisting of Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, and Bi; R.sup.1 is selected from a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.1-C.sub.8 alkylcarbonyl group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, a (R.sup.5.sub.3Si-group, a (R.sup.6R.sup.7N) group, a 4-oxopent-2-en-2-yl group, a C.sub.5-C.sub.12 4-alkoxy-4-oxobuta-2-en-2-yl group, and a C.sub.10-C.sub.16 4-aryloxy-4-oxobuta-2-en-2-yl group; R.sup.2 and R.sup.3 are each independently a hydrogen atom or a C.sub.1-C.sub.8 alkyl group; R.sup.4 is a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, or a C.sub.1-C.sub.8 alkylcarbonyl group; R.sup.5 is a hydroxy group, a C.sub.1-C.sub.8 alkyl group, a C.sub.5-C.sub.12 alicyclic alkyl group, a C.sub.1-C.sub.12 alkoxy group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, or a group having a siloxane bond; a plurality of R.sup.5 may be the same or different; R.sup.6 and R.sup.7 are each independently a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.5-C.sub.12 alicyclic alkyl group, a C.sub.6-C.sub.12 aryl group, a C.sub.7-C.sub.13 aralkyl group, or a C.sub.1-C.sub.12 acyl group; R.sup.6 and R.sup.7 may be linked via a carbon-carbon saturated bond or a carbon-carbon unsaturated bond to form a ring structure; m is an integer that represents the valence of the metal atom M; a is an integer of 1 to (m?2); and b is an integer of 1 to 6, and c is an integer of 1 to 5. Provided is a polymer including a metal-oxygen-metal bond as the main chain that is stably present without aggregating or turning into a gel even in high concentration and high viscosity.

##STR00001##

The method for producing non-core beta silicon carbide fibers includes four steps. The first step is spinning of multifilament polymeric fiber by melt-extrusion of polycarbosilane. The second step is thermooxidative cross-linking for which the produced spun polymeric fibers are cured in an oxidation furnace at a temperature of 175-250 degrees C. at a heating rate of 3-10 degrees C./h until their weight is increased by 6-15%. The third step is carbonization of the produced cured polymeric fibers with the conversion into the ceramic phase. The fourth step is finishing of the produced beta silicon carbide fiber. The effect of the invention is producing non-core silicon carbide fibers, improving their strength performance, improving resistance to high temperatures and their high creep resistance, stable fiber properties, optimal average diameter of fibers, absence of foreign impurities in the fiber composition.

The method of fabricating a photocatalyst for water splitting includes electrospinning a Zn-based solution mixed with CdS nanoparticles and then calcining to produce CdS nanoparticle decorated ZnO nanofibers having significant photocatalytic activity for water splitting reactions. The photocatalyst fabricated according to the method can produce H.sub.2 at a rate of 820 molh.sup.1g.sup.1 catalyst from aqueous solution under light irradiation.

Disclosed are porous multi-metal oxide nanotubes and a production method therefor. In one aspect, methods for producing porous multi-metal oxide nanotubes are provided comprising: (a) preparing an admixture comprising metal-acetylacetonate precursors, polyacrylonitrile (PAN) and a solvent component; and (b) producing a nanocomposite from the admixture, wherein metals of the metal-acetylacetonate precursors comprise a non-radioactive alkali metal stable isotope and a non-radioactive alkaline earth metal stable isotope. As such, porous multi-metal oxide nanotubes having a single-phase multivalence may be obtained in high yield without using harmful chemical substances. In addition, the polymer electrolyte membrane including the porous multi-metal oxide nanotubes may have maintained and improved mechanical strength, and thus may have maintained durability even during cell operation and may also have improved proton conductivity even at low humidity. The fuel cell including the polymer electrolyte membrane may have improved performance.

Disclosed are porous multi-metal oxide nanotubes and a production method therefor. In one aspect, methods for producing porous multi-metal oxide nanotubes are provided comprising: (a) preparing an admixture comprising metal-acetylacetonate precursors, polyacrylonitrile (PAN) and a solvent component; and (b) producing a nanocomposite from the admixture, wherein metals of the metal-acetylacetonate precursors comprise a non-radioactive alkali metal stable isotope and a non-radioactive alkaline earth metal stable isotope. As such, porous multi-metal oxide nanotubes having a single-phase multivalence may be obtained in high yield without using harmful chemical substances. In addition, the polymer electrolyte membrane including the porous multi-metal oxide nanotubes may have maintained and improved mechanical strength, and thus may have maintained durability even during cell operation and may also have improved proton conductivity even at low humidity. The fuel cell including the polymer electrolyte membrane may have improved performance.