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The first commercially viable hydrogen/air performance for a nonprecious metal catalyst–based PEMFC is demonstrated.

A novel, one-step protocol for the selective synthesis of W 2 C nanoparticles from phosphotungstic acid (H 3 PW 12 O 40 ), a low-cost and commercially available tungsten compound, was developed. The nanoparticles had diameters of 1–50 nm and were dispersed on a carbon substrate. The W 2 C nanoparticles were prepared by a simple operation sequence, involving impregnation of carbon black with H 3 PW 12 O 40 followed by calcination at 1000 °C. X-ray diffraction study revealed the selective formation of the W 2 C phase in the samples prepared, whereas the tungsten carbide (WC) phase was present in the control prepared from H 2 WO 4 . Stable W 2 C nanoparticles were obtained using this method owing to the presence of phosphate at the interfaces between the W 2 C nanoparticles and the carbon substrates, which inhibited the diffusion of carbon atoms from the carbon substrates to the W 2 C nanoparticles, leading to the formation of WC. The W 2 C nanoparticles prepared showed an excellent catalytic activity for the hydrogen evolution reaction (HER), with low Tafel slopes of ∼50 mV/decade. The HER catalytic activity was notably high, being comparable to that of MoS 2 , which is a promising alternative to Pt. The present method can potentially be applied to produce highly effective, low-cost, Pt-free electrocatalysts for the HER.

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Carbon-based oxygen reduction reaction (ORR) catalysts are regarded as a promising candidate to replace the currently used Pt catalyst in polymer electrolyte fuel cells (PEFCs); however, the active sites remain under discussion. We predicted that warped graphitic layers (WGLs) are responsible for the ORR catalytic activity in some carbon catalysts (i.e., carbon alloy catalysts (CACs)). To prove our assumption, we needed to use WGLs consisting of carbon materials, but without any extrinsic catalytic elements, such as nitrogen, iron, or cobalt, which effectively enhance ORR activity. The present study employed a fullerene extraction residue as a starting material to construct WGLs. The oxidation of the material at 600 °C exposed the WGLs by removing the surrounding amorphous moieties. Transmission electron microscopy (TEM) observations revealed the formation of WGLs by oxidation treatment at 600 °C in an O2/N2 stream. Extending the oxidation time increased the purity of the WGL phase, but also simultaneously increased the concentration of oxygen-containing surface functional groups as monitored by temperature programmed desorption (TPD). The specific ORR activity increased with oxidation up to 1 h and then decreased with the intensive oxidation treatment. Correlations between the specific ORR activity and other parameters confirmed that the development of the WGL and the increase in the O/C ratio are the competing factors determining specific ORR activity. These results explain the maximum specific ORR activity after 1 h of oxidation time. WGLs were found to lower the heat of adsorption for O2 and to increase the occurrence of heterogeneous electron transfer.