The chemical bath deposition (CBD) method was successfully applied to prepare WTiO nanotube arrays co-deposited with chromium, iron and chromium-iron nanoparticles. Various methods have been used in the characterization of synthetic co-deposited nanostructures. WTiO nanotubes can keep the nanotubular structures at low iron concentration in the CBD solution, as indicated by our FESEM results. Iron and chromium can be applied to improve the absorption capability of the WTiO nanotubes for the visible-light, according to the UV-Vis results. Based on the photoelectrochemical performance and photocatalytic hydrogen evolution characteristics of the CrFeWTiO catalysts, the co-deposited nanoparticles contribute to the improvement in the photocatalytic efficiency. The best photocatalytic activity was shown by the CrFeWTiO-1 sample formed by immersion in a CBD solution containing 0.08 M ClCl·6HO + 0.02 M FeCl·6HO. The hydrogen evolution reaction of the new photocatalysts showed that their photocatalytic activity was very stable. A facile method has been developed in this study for the synthesis of high performance co-deposited photocatalysts with excellent stability and reliability in photoelectrochemical water splitting. A stable and high photocatalytic activity for hydrogen evolution in the absence of a Pt co-catalyst was exhibited by the novel CrFeWTiO compounds prepared.

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The cathode catalyst layer void volume of the proton exchange membrane fuel cell (PEMFC) determines the available three‐phase regions and routes of mass transfer in the membrane electrode assembly (MEA). In this paper, four MEAs with different void volume of cathode catalyst layer have been made and their performance was evaluated and analyzed. The results show that for the MEA with cathode catalyst layer porosity of 20.8%, an optimal structure and a proper balance between catalyst layer void volume and Nafion content is obtained. The optimal void volume caused that electrochemical surface area for the MEA with the optimal structure be 1.45 times higher than MEA having a porosity of 29.5% at the end of the long‐term cycles. On the other hand, the mass transfer resistance (Rmt) at the end of long‐term cycles for MEA with the optimal structure is 4.8 times less than the same MEA having a porosity of 15.9%. This fact makes that MEA with the cathode catalyst layer porosity of 20.8%, both in short and in the long‐term, has higher and more stable performance than other MEAs; so that its maximum output power density has changed only 0.8% during 200 cycles.