An object is to provide an electrode catalyst layer, a membrane electrode assembly, and a polymer electrolyte fuel cell that can suppress decrease in durability of the membrane electrode assembly and decrease in power generation performance of the polymer electrolyte fuel cell by suppressing crack generation in the electrode catalyst layer. An electrode catalyst layer according to one aspect of the present invention is an electrode catalyst layer including at least: a catalytic substance; aggregates of polymer electrolytes; and polymer electrolyte fibers. In the electrode catalyst layer, an amount of phosphorus and an amount of platinum defined via elemental analysis by energy dispersive X-ray spectroscopy (EDX) satisfy a following equation (1)
0<P/Pt3.0Equation (1).

An object is to provide an electrode catalyst layer, a membrane electrode assembly, and a polymer electrolyte fuel cell that can suppress decrease in durability of the membrane electrode assembly and decrease in power generation performance of the polymer electrolyte fuel cell by suppressing crack generation in the electrode catalyst layer. An electrode catalyst layer according to one aspect of the present invention is an electrode catalyst layer including at least: a catalytic substance; aggregates of polymer electrolytes; and polymer electrolyte fibers. In the electrode catalyst layer, an amount of phosphorus and an amount of platinum defined via elemental analysis by energy dispersive X-ray spectroscopy (EDX) satisfy a following equation (1)
0<P/Pt3.0Equation (1).

Improved performance ion exchange membranes for use in PEM, AEM and DMFC fuel cells, buffered fuel cells, hydrolysis, other applications comprise a molecular matrix of homopolymers, di-monomer, heteropolymers, copolymers, or block-polymers of fluorocarbon and hydrocarbon compounds combined with (i) skeletal support grid to improve durability, handling, reduce membrane swelling, and sequester dopants and nanoparticles from leakage; (ii) microporous membrane formed using a sacrificial filler process enhancing conductivity and limiting fuel crossover; (iii) hetero-ionomeric matrix of two-or-more membrane-bound acids e.g. sulphonic and phosphonic acid expanding usable range; (iv) permanent fillers enhancing conductivity and porosity including nanoparticles, metal-oxides, zeolites, silicates, GOs, CNTs, MOFs, POSS, and others; (v) ionic liquid doping to enhance membrane conductivity; (vi) membrane nanocoating preventing H.sub.2O.sub.2 diffusion; and/or (vii) catalytic nanocoating with metals, metal-oxides, and MOFs preventing atmospheric toxin catalyst poisoning. Combined with a heterogenous GDL, the IEM is integrated into iBFC power blade and energy bank applications.

Improved performance ion exchange membranes for use in PEM, AEM and DMFC fuel cells, buffered fuel cells, hydrolysis, other applications comprise a molecular matrix of homopolymers, di-monomer, heteropolymers, copolymers, or block-polymers of fluorocarbon and hydrocarbon compounds combined with (i) skeletal support grid to improve durability, handling, reduce membrane swelling, and sequester dopants and nanoparticles from leakage; (ii) microporous membrane formed using a sacrificial filler process enhancing conductivity and limiting fuel crossover; (iii) hetero-ionomeric matrix of two-or-more membrane-bound acids e.g. sulphonic and phosphonic acid expanding usable range; (iv) permanent fillers enhancing conductivity and porosity including nanoparticles, metal-oxides, zeolites, silicates, GOs, CNTs, MOFs, POSS, and others; (v) ionic liquid doping to enhance membrane conductivity; (vi) membrane nanocoating preventing H.sub.2O.sub.2 diffusion; and/or (vii) catalytic nanocoating with metals, metal-oxides, and MOFs preventing atmospheric toxin catalyst poisoning. Combined with a heterogenous GDL, the IEM is integrated into iBFC power blade and energy bank applications.