Metal Chalcogenides on Silicon Photocathodes for Efficient Water Splitting: A Mini Overview

Abstract

In the photoelectrochemical (PEC) water splitting (WS) reactions, a photon is absorbed by a semiconductor, generating electron-hole pairs which are transferred across the semiconductor/electrolyte interface to reduce or oxidize water into oxygen or hydrogen. Catalytic junctions are commonly combined with semiconductor absorbers, providing electrochemically active sites for charge transfer across the interface and increasing the surface band bending to improve the PEC performance. In this review, we focus on transition metal (di)chalcogenide [TM(D)C] catalysts in conjunction with silicon photoelectrode as Earth-abundant materials systems. Surprisingly, there is a limited number of reports in Si/TM(D)C for PEC WS in the literature. We provide almost a complete survey on both layered TMDC and non-layered transition metal dichalcogenides (TMC) co-catalysts on Si photoelectrodes, mainly photocathodes. The mechanisms of the photovoltaic power conversion of silicon devices are summarized with emphasis on the exact role of catalysts. Diverse approaches to the improved PEC performance and the proposed synergetic functions of catalysts on the underlying Si are reviewed. Atomic layer deposition of TM(D)C materials as a new methodology for directly growing them and its implication for low-temperature growth on defect chemistry are featured. The multi-phase TM(D)C overlayers on Si and the operation principles are highlighted. Finally, challenges and directions regarding future research for achieving the theoretical PEC performance of Si-based photoelectrodes are provided.

Enhancing the Hydrogen Evolution Properties of Kesterite Absorber by Si‐Doping in the Surface of CZTS Thin Film

“…Two depletion regions (kesterite layer/CdS and electrode–electrolyte interface) present in the heterostructure samples allow the formation of photogenerated e − –h + pairs within the photoelectrode and near the surface. [ 52 ] It can be noticed that Si‐doped samples show improved photocurrent density in both kinds of samples, pristine and heterostructure photocathodes. Enhancement in the PEC performance in Si‐doped samples can be attributed to the steep band bending at grain boundaries of the absorber in contrast to that of CZTS (Figure 7).…”

Pulsed Laser Deposition of Nanostructured MoS3/np-Mo//WO3−y Hybrid Catalyst for Enhanced (Photo) Electrochemical Hydrogen Evolution

“…The nanostructured films containing WO 3− y and MoS 2 phases are currently used to create photoanodes for effective photo-electrochemical water oxidation reaction (oxygen evolution reaction, OER) [2,3,9,55,56,57]. This is due to the adequate optical properties of these semiconductor materials and their energy band structures.…”

“…The effective and low-cost production of this gas energy source without spending natural hydrocarbon raw materials largely determines the successful development and implementation of alternative (green/hydrogen) energetics. A significant reduction in energy consumption during the hydrogen evolution by photo-activated electrolysis is dependent on the success of the development and creation of new efficient non-precious electrocatalysts and photo-electrocatalysts, the manufacture of which does not use expensive materials (platinum group metals) [1,2,3,4,5,6]. Recently, a motivated interest has been formed in nanostructured and hybrid materials containing chalcogenides, phosphides, nitrides, carbides, or oxides of transitional metals [7,8,9,10,11,12].…”

Acceptor‐Doping Accelerated Charge Separation in Cu2O Photocathode for Photoelectrochemical Water Splitting: Theoretical and Experimental Studies

“…In various sustainable hydrogen production routes, photoelectrochemical (PEC) water splitting has drawn increasing attention since 1972 . Numerous materials, including Si, g‐C 3 N 4 , metal oxides, metal‐chalcogenides, phosphides, and perovskites, etc., have been employed for PEC water splitting. Especially, metal oxides have shown promising prospects owing to their attractive light‐harvesting ability, redox‐compatible energy levels, low cost, and high repeatability.…”