Synergetic photocatalytic and thermocatalytic aqueous phase reforming of methanol for hydrogen production based on noble metal/photosensitive supports catalysts

To overcome high Gibbs free energy and low reaction rate of thermal catalytic and photocatalytic hydrogen production from methanol-H2O mixture, photo-thermal synergistic catalysis (PC-TC) reforming has proved to be an effective strategy owing to the photo-assited thermal synergistic effect to accelerate the step controlling kinetic behavior. In order to efficiently produce H2, proper photosensitive catalysts which absorb light energy and also show efficient thermal catalytic (TC) performance need to be developed. To study the designing principle for catalysts, herein we incorporate Pt/Pd and three different supports which show similar band gaps (ZnO, CeO2, and P25) through the in-situ photo-deposition, which act as catalysts for PC-TC methanol aqueous reforming. The resultant 0.1%Pt/P25 catalyst exhibits H2 evolution activity ∼3.1 times than that of the TC condition and ∼5.5 times than that of the photocatalytic reforming (PC) condition in the proposed PC-TC process; meanwhile 0.1%Pt/ZnO and 01%Pt/CeO2 under PC-TC condition show ∼1.3 times and ∼2.0 times than that of the catalytic performance under TC condition. The physical characterizations prove that the metal-support interaction and the supports may be key factors for the catalytic performance. The active intermediate trapping experiments demonstrate possible intermediates in the PC-TC process and established reaction mechanisms to explain the synergetic effect for improved efficiency of hydrogen production. These findings may open up a new avenue of designing catalysts based on semiconductors for the PC-TC reforming of methanol-water to produce hydrogen in a high-efficiency and low-cost way, serving the needs of the future hydrogen economy.