such as global warming and climate changes. [1][2][3][4] Solar energy is clean and abundant, for example, nearly four million exajoules (4 × 10 18 J) of solar energy reaches the earth annually. [1,5] Conversion of solar energy into chemical energy through photocatalytic decomposition of water to produce hydrogen is one of the suitable approaches to utilize solar energy. [6][7][8][9][10] The different types of fundamental photocatalytic reactions include i) semiconductor-based photocatalysis, ii) dye-sensitized semiconductor-based photo catalysis, iii) quantum dot-based photocatalysis, iv) 2D layered materials-based photocatalysts, and v) plasmonic photocatalysts. [11] Photocatalytic hydrogen evolution reaction (HER) are mainly based on inorganic semiconductor and poly merbased organic semiconductors, for exampl, in a conventional dye-sensitized semiconductor photocatalytic hydrogen production system, the dye molecules are excited to inject electrons into the conduction band of a semiconductor or polymer (inorganic semiconductor TiO 2 or g-C 3 N 4 is usually chosen), then the electrons are quickly captured by the co-catalyst (such as precious metals Efficient photocatalytic hydrogen evolution reaction (HER) in the visibleto-near infrared region at a low cost remains a challenging issue. This work demonstrates the fabrication of organic-inorganic composites by deposition of supramolecular aggregates of a chlorophyll derivative, namely, zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide a (Chl) on the surface of Ti 3 C 2 T x MXene with 2D accordion-like morphology. This composite material isemployed as noble metal-free catalyst in photocatalytic HER under the white light illumination, where Chl serves as a small molecule organic semiconductor component instead of ordinary inorganic and polymer organic semiconductors such as TiO 2 and g-C 3 N 4 , and Ti 3 C 2 T x serves as a co-catalyst. Different composition ratios of Chl/Ti 3 C 2 T x are compared for their light-harvesting ability, morphology, charge transfer efficiency, and photocatalytic performance. The best HER performance is found to be as high as 52 ± 5 µmol h −1 g cat −1 after optimization. Such a large HER activity is attributed to the efficient light harvesting followed by exciton transfer in Chl aggregates and the resultant charge separation at the interface of Chl/Ti 3 C 2 T x .

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Chlorophylls (Chls) are the most naturally abundant organic dye pigments on earth. However, there is little research on Chl polymers so far. In this paper, we demonstrate the fabrication of a series of polymerized chlorophyll-a derivatives with different central metals (PolyMChls, M = Mg, Co, Ni, Cu, Zn, and Ga) via the electrochemical coupling of a peripheral vinyl group at the C3-position on the chlorin macrocycle. The formation of PolyMChls is confirmed by the broadening and slight red-shift of the Soret band in their ultraviolet–visible absorption spectra. PolyMChl films yield a morphology of uniform stacked nanospheres (PolyCuChl ∼ 237 nm), while the original MChl particles are irregular with a size of about 10 μm by scanning electron microscopy. When these PolyMChl films are employed as the working electrodes in a three-electrode system, the highest capacitance of 334 F g–1 at 5 mV s–1 is obtained for PolyCuChl. Basing on the widely existing Chl derivatives, we find a new biopolymer family. The great potential of biopolymer PolyMChl is also exhibited in the energy storage area.

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