Towards Highly Efficient Chalcopyrite Photocathodes for Water Splitting: The Use of Cocatalysts beyond Pt

Abstract

Solar radiation is a renewable and clean energy source used in photoelectrochemical cells (PEC) to produce hydrogen gas as a powerful alternative to carbon-based fuels. Semiconductors play a vital role in this approach, absorbing the incident solar photons and converting them into electrons and holes. The hydrogen evolution reaction (HER) occurs in the interface of the p-type semiconductor that works as a photocathode in the PEC. Cu-chalcopyrites such as Cu(In, Ga)(Se,S) 2 (CIGS) and CuIn(Se,S) 2 (CIS) present excellent semiconductor characteristics for this purpose, but drawbacks as charge recombination, deficient chemical stability, and slow charge transfer kinetics, demanding improvements like the use of n-type buffer layer, a protective layer, and a cocatalyst material. Concerning the last one, platinum (Pt) is the most efficient and stable material, but the high price due to its scarcity imposes the search for inexpensive and abundant alternative cocatalyst. The present Minireview highlighted the use of metal alloys, transition metal chalcogenides, and inorganic carbon-based nanostructures as efficient alternative cocatalysts for HER in PEC.

Coating of gallium-based liquid metal particles with molybdenum oxide and oxysulfide for electronic band structure modulation

“…57 On the other hand, MoS x is a semiconductor with stronger UV-Vis absorption and a lower band gap of 1.1 eV. 58 Hence, when the surface of liquid metal particles was decorated with MoO x S y , the UV-Vis absorption of EGaIn@MoO x S y particles was enhanced (Fig. 4c) and the optical band gap further dropped to 2.7 eV (Fig.…”

Gamma-irradiated stibnite thin films set a remarkable benchmark performance for photoelectrochemical water splitting

“…It is constructed using cost-effective semiconductor materials, making it a practical choice for this purpose. 8 Presently, the most reported low-cost photoelectrodes are composed of semiconductors, such as CuIn x Ga (1− x ) Se 2 , 9 CuBi 2 O 4 (ref. 10 ), and Cu 2 O.…”

Organic semiconductor-BiVO4 tandems for solar-driven H2O and CO2 splitting

“…1 PEC devices mimic photosynthesis as they couple light absorbers with suitable catalysts to directly harness, convert and store abundant solar energy in the form of chemical fuels. 2 Such integrated 'artificial leaf' devices employ a wide range of photoactive materials including silicon, [3][4][5] Cuchalcopyrite, 6,7 Cu2O, 8 perovskite, [9][10][11] III-V and II-VI semiconductors. [12][13][14] However, these PEC systems often face challenges in terms of insufficient photovoltage, moisture stability, material cost or toxicity.…”