Membrane-Inspired Acidically Stable Dye-Sensitized Photocathode for Solar Fuel Production

Abstract

Tandem dye-sensitized photoelectrochemical cells (DSPECs) for water splitting are a promising method for sustainable energy conversion but so far have been limited by their lack of aqueous stability and photocurrent mismatch between the cathode and anode. In nature, membrane-enabled subcellular compartmentation is a general approach to control local chemical environments in the cell. The hydrophobic tails of the lipid make the bilayer impermeable to ions and hydrophilic molecules. Herein we report the use of an organic donor-acceptor dye that prevents both dye desorption and semiconductor degradation by mimicking the hydrophobic/hydrophilic properties of lipid bilayer membranes. The dual-functional photosensitizer (denoted as BH4) allows for efficient light harvesting while also protecting the semiconductor surface from protons and water via its hydrophobic π linker. The protection afforded by this membrane-mimicking dye gives this system excellent stability in extremely acidic (pH 0) conditions. The acidic stability also allows for the use of cubane molybdenum-sulfide cluster as the hydrogen evolution reaction (HER) catalyst. This system produces a proton-reducing current of 183 ± 36 μA/cm(2) (0 V vs NHE with 300 W Xe lamp) for an unprecedented 16 h with no degradation. These results introduce a method for developing high-current, low-pH DSPECs and are a significant move toward practical dye-sensitized solar fuel production.

Solar H2 evolution in water with modified diketopyrrolopyrrole dyes immobilised on molecular Co and Ni catalyst–TiO2 hybrids

“…Light-driven H 2 evolution with organic dyes in combination with a metal oxide semiconductor has been previously reported, but these systems required either a Pt co-catalyst, a p-type semiconductor electrode, organic solvents or an anchor-free diffusional dye. 8,27–30 Only few studies are available with organic chromophores under DSP conditions and even less with commonly used aqueous electron donors, such as triethanolamine (TEOA) or ascorbic acid (AA), or with a molecular catalyst in a semi-heterogeneous photocatalytic scheme. 11,31–34 …”

Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells

“…The design of photosensitizers for p-type semiconductor (p-SC) based dye sensitized solar cells (DSSCs) has drawn attention, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] due to the possible applications in photocatalysis [15][16][17][18] and because it is indispensable for the development of the tandem dye sensitized solar cells. [19][20][21][22][23][24] The photosensitizer is one of the crucial components, which controls the overall performance of the solar cell.…”

Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes

“…One of the main concerns at the basis of the development of PECs for water splitting [71] which produce molecular H 2 at the (photo)cathode and O 2 at the (photo)anode is the replacement of precious metals like Pt or Ru photoelectrocatalysts with durable semiconducting electrodes of p-type based on cheaper metal oxides, phosphides and sulfides/disulfides or Si, in order to photoactivate HER (hydrogen evolution reaction). Due to the wide employment in p-DSCs, NiO photocathodes have been considered also for the application of photoelectrochemical generation of H 2 in a variety of sensitization schemes and surface decorations (Figures 11-14) [36,[72][73][74][75][76][77][78][79].…”

“…The picture evidences the blocking effect exerted by the hexyl groups against direct H + discharge onto bare NiO cathode (corresponding to a dark shunt effect). Reproduced with permission from reference [75].…”

“…Upon excitation of the QD this transfers an electron to the co-catalyst (usually a metal complex) and receives an electron from NiO in order to get regenerated for a successive cycle. Two main types of photocathode configuration have been identified with NiO surface being sensitized by a colorant (either organometallic (Figure 11) or organic ( Figure 12)), which is electronically connected to the actual electrocatalyst of molecular hydrogen formation [74,75]. Another main typology of photocathode configuration is represented by the sensitization of NiO with quantum dots (QD) made of a second p-type semiconducting material with lowered VB edge with respect to NiO, e.g., CdSe (Figures 13 and 14) [72,78].…”