On the Design of Donor–Acceptor Conjugated Polymers for Photocatalytic Hydrogen Evolution Reaction: First-Principles Theory-Based Assessment

Abstract

A set of fluorene-based polymers with a donor−acceptor architecture has been investigated as a potential candidate for photocatalytic hydrogen evolution reaction. A design protocol has been employed based on first-principles theory and focusing on the following properties: (i) broad absorption spectrum to promote a higher number of photogenerated electron−hole pairs, (ii) suitable redox potentials, and (iii) appropriate reaction thermodynamics using the hydrogen-binding energy as a descriptor. We have found that the polymers containing a fused-ring acceptor formed by benzo(triazole-thiadiazole) or benzo(triazole-selenodiazole) units display a suitable combination of such properties and stand out as potential candidates. In particular, PFO-DSeBTrT (poly (9,9′-dioctylfluorene)-2,7-diyl-alt-(4,7-bis(thien-2yl)-2-dodecyl-benzo-(1,2c:4,5c′)-1,2,3-triazole-2,1,3-selenodiazole)) has an absorption maximum at around 950 nm for the highest occupied molecular orbital−lowest unoccupied molecular orbital transition, covering a wider range of solar emission spectrum, and a reduction catalytic power of 0.78 eV. It also displays a calculated hydrogen-binding free energy of ΔG H = 0.02 eV, which is lower in absolute value than that of Pt (ΔG H ≈ −0.10 eV). Furthermore, the results and trends analysis provide guidance for the rational design of novel photo-electrocatalysts.

Advances in sodium secondary batteries utilizing ionic liquid electrolytes

“…However, the large polarisation of Na metal sometimes makes the accurate evaluation of target electrodes difficult when using a half-cell configuration. 86,124,[239][240][241][242] Fig. 8 summarises some information on Na metal deposition-dissolution.…”

Hydrogen evolution by polymer photocatalysts; a possible photocatalytic cycle

“…the lowest hydrogen absorption free energy predicted for organic materials (0.02 eV). 74 Finally, to probe the barrier to H 2 evolution we performed a constrained optimization, starting from a fully optimized tail-totail cluster of two PP 2 -H • -H 2 O molecules, where we step-by-step stretch the σ C-H bonds decreasing the H-H distance. We keep the two phenyl rings furthest away from the forming H 2 molecule fixed at all points along the scanning coordinate and take the hydrogen binding site as C 1 rather than C 3 as this allowed us to construct a reaction coordinate where the shortening of the hydrogen-hydrogen distance and the subsequent flattening of the two phenyl rings, on which the hydrogen atoms were adsorbed, were the only major structural changes.…”

The Role of Computational Chemistry in Discovering and Understanding Organic Photocatalysts for Renewable Fuel Synthesis

“…More recently, they extended the scope of their calculations, albeit this time using the DFT exchange‐correlation functional M06, to the adsorption of hydrogen on BT units in oligomers in which those BT units have been substituted with electron donating or withdrawing groups; BT units where the sulfur has been replaced with selenium, and in which they changed the co‐monomers; as well as oligomers in which hydrogen adsorbs on the nitrogen atoms of fused BT‐triazole polymers. [ 97,98 ] Adsorbing a hydrogen atom on one of the two nitrogen atoms of the fused selenium containing BT unit was predicted to be especially favorable with a predicted Δ G H of 0.02 eV, very close to the optimum value of 0 and very similar to that predicted for platinum. Adsorption of hydrogen on carbon atoms was recently studied by Prentice et al., [ 101 ] who reported a value of 1.2 eV for adsorption on aromatic −C[H]− carbons atoms in the case of poly( p‐ phenylene).…”