Pd Nanoparticles Supported on N-Doped TiO₂ Nanosheets: Crystal Facets, Defective Sites, and Metal–Support Interactions Boost Reforming of Formaldehyde Solution for Hydrogen Production

Abstract

To produce H2 from formaldehyde (HCHO), dehydrogenation offers an alternative approach to future hydrogen-based energy sources, but the unsatisfactory efficiency hinders its practical application. Here, ultrafine Pd nanoparticle (NP) decorated N-doped TiO2 nanosheets exposed with (001) facet catalysts (denoted as Pd/TiO2–x ) have been prepared and exhibit superior H2 production performance from alkaline HCHO aqueous solution. Under our current conditions, the Pd/TiO2–x catalyst with a Pd loading of 1 wt % exhibits a H2 production rate of 183.77 mL/min/g, which is 1.75 and 3.66 times that of Pd/TiO2 and Pd NPs, respectively. Based on the results of Fourier transform infrared spectroscopy (FTIR), Raman, and liquid-phase electron paramagnetic resonance (EPR) spin-trapping experiments, the excellent H2 generation of Pd/TiO2–x can be attributed to the synergistic contribution among the reactive crystal facets, defective sites, and metal–support interactions in boosting the breakage of C–H bonds in HCHO, dissociation of H2O, and ultimately the formation of H2. This work is expected to provide a paradigm of an efficient catalyst to produce H2 from HCHO/H2O solution.

Construction of Highly Active Pd–Ti3+ Sites in Defective Pd/TiO2 Catalysts for Efficient Hydrogenation of Styrene–Butadiene–Styrene

“…This is because the Pd NPs are partially encapsulated by TiO 2 layers during the reduction process, thus exposing less Pd surface and suppressing the CO adsorption on Pd. This result also provides solid evidence to prove the strong interaction between Pd and the TiO 2 supports. , …”

“…This result also provides solid evidence to prove the strong interaction between Pd and the TiO 2 supports. 45,46 Figure 2g−i show the high-resolution TEM images of all catalysts, and the clear lattice fringes indicate that samples are well-crystallized, and the distance of lattice space is determined to be 0.35 nm, which is ascribed to the (101) facet of anatase TiO 2 (JCPDS 21-1272). Additionally, the distance of lattice space of Pd NPs (insets in Figure 2g−i) is 0.22 nm, which can be assigned to (111) of cubic Pd (JCPDS 46-1043).…”

Flexible Antibacterial Respiratory Monitoring Sensor Based on Controllable Au-Modified Surface of Highly {001} Preferred Anatase Titanium Dioxide Thin Film

“…13 Meanwhile, facet engineering of TiO 2 is widely employed to optimize its photocatalytic performance, such as exposing {001} or {101} facets to facilitate the separation between photoelectrons and photoholes. 13−15 Notably, the {001} facet of anatase TiO 2 contains a high density of surface oxygen and five-coordinated unsaturated titanium atoms, 16 performance. 17 All of these findings suggest that highly {001} preferred anatase TiO 2 thin films would be advantageous.…”

“…In addition, anatase TiO 2 has a unique indirect band gap, so the lifetime of photogenerated electron–hole pairs in anatase TiO 2 is longer and the reaction probability is improved . Meanwhile, facet engineering of TiO 2 is widely employed to optimize its photocatalytic performance, such as exposing {001} or {101} facets to facilitate the separation between photoelectrons and photoholes. − Notably, the {001} facet of anatase TiO 2 contains a high density of surface oxygen and five-coordinated unsaturated titanium atoms, thus exhibiting a high surface energy and reactivity with great sensing performance . All of these findings suggest that highly {001} preferred anatase TiO 2 thin films would be advantageous.…”

Pyrrolic Nitrogen Boosted H2 Generation from an Aqueous Solution of HCHO at Room Temperature by Metal-Free Carbon Catalysts

“…Among the various liquid hydrogen storage systems, formaldehyde (HCHO) emerges as a prominent candidate, owing to its sustainability, cost-effectiveness, and abundant availability through biomass conversion. − Importantly, the generation of H 2 from an aqueous solution of HCHO efficiently utilizes one H atom from H 2 O to release H 2 while simultaneously producing valuable formic acid (HCOOH) instead of unnecessary CO 2 and/or CO. − Thermodynamically, this exothermic process typically requires low temperatures to enhance the forward reaction equilibrium. However, the efficient activation of both HCHO and H 2 O at low temperatures suffers a significant challenge that limits the H 2 generation from an aqueous solution of HCHO. ,, …”