Carbon dioxide mediated, reversible chemical hydrogen storage using a Pd nanocatalyst supported on mesoporous graphitic carbon nitride

Abstract

Reversible, carbon dioxide mediated chemical hydrogen storage was first demonstrated using a heterogeneous Pd catalyst supported on mesoporous graphitic carbon nitride (Pd/mpg-C 3 N 4 ). The Pd nanoparticles were found to be uniformly dispersed onto mpg-C 3 N 4 with an average size of 1.7 nm without any agglomeration and further exhibit superior activity for the dehydrogenation of formic acid with a turnover frequency of 144 h À1 even in the absence of external bases at room temperature. Initial DFT studies suggest that basic sites located at the mpg-C 3 N 4 support play synergetic roles in stabilizing reduced Pd nanoparticles without any surfactant as well as in initiating H 2 -release by deprotonation of formic acid, and these potential interactions were further confirmed by X-ray absorption near edge structure (XANES). Along with dehydrogenation, Pd/mpg-C 3 N 4 also proves to catalyze the regeneration of formic acid via CO 2 hydrogenation. The governing factors of CO 2 hydrogenation are further elucidated to increase the quantity of the desired formic acid with high selectivity.

Oxygenated monolayer carbon nitride for excellent photocatalytic hydrogen evolution and external quantum efficiency

“…It is well known that features A and B in Figure 4b can be assigned to the π* excitations of pyridinic-type and graphitic-type N species in the g-C 3 N 4 ring structure, respectively. 47,48 The broad feature D can be attributed to the σ* excitation of C-N-C or C-N (N-3C bridging) bonds. 47,48 Interestingly, the π* excitations from the ring structure have almost no change with the introduction of oxygen, while the σ* excitation of C-N bonds shows obviously decreased intensity.…”

Nanogap Engineered Plasmon‐Enhancement in Photocatalytic Solar Hydrogen Conversion

“…The two fi ne peaks at around 397.96 and 400.74 eV correspond to the π* antibond orbitals of the pyridinic and graphitic N species. [ 53,54 ] Depending on the energy, the lower part of the XAS (around 397.96 eV) corresponds to the unoccupied states near the conduction band minimum (CBM); while the higher part (around 400.74 eV) corresponds to the unoccupied states far above the CBM. The N K-edge of g-C 3 N 4 with and without visible light irradiation is presented in Figure 5 a.…”

Efficient production of hydrogen from formic acid using a Covalent Triazine Framework supported molecular catalyst

“…[7][8][9][10] The requirement of a heterogeneous catalytic system has been questioned, [11] yet the aim of developing an air-stable, solid catalyst that produces hydrogen seems justified as it would certainly present advantages in handling and recycling, two important parameters in device-based applications (for example, fuel cells). Whereas the majority of these attempts focus on the use of nanoparticles, [13][14][15][16][17] promising reports involve the use of molecular catalysts. In comparison with homogeneous catalytic systems, suppression of the undesired dehydration reaction (HCOOH!H 2 O + CO) [12] remains an obstacle, and TOFs and corresponding rates per unit reactor volume are often low.…”