Aluminum Titania Nanoparticle Composites as Nonprecious Catalysts for Efficient Electrochemical Generation of H₂

Abstract

In this paper, we demonstrated, for the first time, aluminum titania nanoparticle (Al-TiO2 NP) composites with variable amounts of TiO2 NPs as nonprecious active catalysts for the electrochemical generation of H2. These materials were synthesized by mixing desired amounts of hydrogen titanate nanotubes (TNTs), fabricated here by a cost-effective approach at moderate hydrothermal conditions, with aluminum powder (purity 99.7%; size 35 μm). The mixture was compacted under an applied uniaxial stress of 300 MPa followed by sintering at 500 °C for 1 h. After sintering had been completed, all TNTs were found to convert to TiO2 NPs (average particle size 15 nm). Finally, Al-xTiO2 NP nanocomposites (x = 1, 3, 5, and 10) were obtained and characterized by scanning electron microscopy/energy-dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscopy. The hydrogen evolution reaction (HER) activity of these materials was studied in 0.5 M H2SO4 at 298 K using polarization and impedance measurements. The nanocomposite of chemical composition Al-5% TiO2 NPs showed the best catalytic performance for the HER, with an onset potential (EHER), a Tafel slope (βc), and an exchange current density (j0) of -100 mV (RHE), 59.8 mV decade(-1), and 0.14 mA cm(-2), respectively. This HER activity is not far from that of the commercial platinum/carbon catalyst (EHER = 0.0 mV, βc = 31 mV dec(-1), and j0 = 0.78 mA cm(-2)). The best catalyst also exhibited good stability after 10000 repetitive cycles with negligible loss in current.

MoS2 nanotubes loaded with TiO2 nanoparticles for enhanced electrocatalytic hydrogen evolution

“…[28][29][30] Titanium dioxide (TiO 2 ) is rather inexpensive, relatively non-toxic, and excellent physical and chemical stability in acidic media. [31][32][33][34] Most of the MoS 2 /TiO 2 hetero-structures such as nanoowerlike MoS 2 @TiO 2 nanohybrids, 35,36 39,40 and TiO 2 @MoS 2 nanotube array 41 were used to improve the electrocatalytic hydrogen evolution activity and photocatalytic reaction. As for HER, loading TiO 2 on MoS 2 support cannot only activate the sites of MoS 2 nanotubes, but also utilizes high mobility MoS 2 frame as a bridge for charge transport.…”

Crystalline ZnO and ZnO / TiO 2 nanoparticles derived from tert ‐butyl N‐(2 mercaptoethyl)carbamatozinc( II ) chelate: Electrocatalytic studies for H 2 generation in alkaline electrolytes

“…The turnover frequency (TOF), referring to the amount of hydrogen molecules generated per second per active site, 83,84 was also estimated to further assess the catalyst activity per catalyst site at a specified over‐potential. As reported elsewhere, 85 specific surface area values of the studied catalysts acquired from BET have been used to calculate TOF. A TOF value of 2.2 H 2 /s per active site was recorded by the GC‐(ZnO/TiO 2 ) catalyst at 0.2 V vs RHE.…”

Enhanced hydrogen evolution reaction on highly stable titania‐supported PdO and Eu2O3nanocomposites in a strong alkaline solution

“…The GC‐loaded TiO 2 NP cathode (curve 2) exhibited much lower E HER (−390 mV vs. RHE) value and higher catalytic currents than the bare GC (curve 1). These results indicate that the loaded TiO 2 NPs still possess considerable catalytic activity for the HER, even in the dark …”

“…Turnover frequency (TOF), which refers to the number of hydrogen molecules produced per second per active site, was also estimated to further evaluate the activity of the catalyst for the HER per site of a catalyst at a given overpotential. Specific surface area values of the studied catalysts obtained from BET were used to calculate TOF, as reported elsewhere . The PdO/TiO 2 catalyst recorded a TOF value of 2.3 H 2 /s per active site at 0.2 V versus RHE, which almost doubles that calculated for Eu 2 O 3 /TiO 2 (1.25 H 2 /s per active site) at the same overpotential.…”