Creation of 3D Textured Graphene/Si Schottky Junction Photocathode for Enhanced Photo‐Electrochemical Efficiency and Stability

Abstract

This work presents a novel photo‐electrochemical architecture based on the 3D pyramid‐like graphene/p‐Si Schottky junctions. Overcoming the conventional transfer technique by which only planar graphene/Si Schottky junctions are currently available, this work demonstrates the 3D pyramid‐like graphene/p‐Si Schottky junction photocathode, which greatly enhances light harvesting efficiency and exhibits promising photo‐electrochemical performance for hydrogen generation. The formation of 3D pyramid‐like graphene/p‐Si Schottky junctions exhibits enhanced electrochemical activity and promotes charge separation efficiency compared with the bare pyramid Si surface without graphene. The inherent chemical inertness of graphene significantly improves the operational stability of 3D graphene/p‐Si Schottky junction photo‐electrochemical cells. The 3D pyramid‐like graphene/p‐Si Schottky junction photocathode delivers an onset potential of 0.41 V and a saturated photocurrent density of −32.5 mA cm−2 at 0 V (vs RHE) with excellent stability comparable to values reported for textured or nanostructured p‐Si photocathodes coated with ultrathin oxide layers by the conventional atomic layer deposition technique. These results suggest that the formation of graphene/Si Schottky junctions with a 3D architecture is a promising approach to improve the performance and durability of Si‐based photo‐electrochemical systems for water splitting or solar‐to‐fuel conversion.

Challenges and prospects about the graphene role in the design of photoelectrodes for sunlight-driven water splitting

“…The formation of pyramid-like Si/graphene Schottky junctions with a 3D architecture ( Fig. 9a ) showed to be a promising approach to improve the performance and durability of Si-based PEC systems for water splitting 41 and reflect the excellent role of SLG as passivation layer which remains a relatively stable current during 30 h ( Fig. 9b ).…”

“…Compared to graphite and carbon nanotubes, graphene exhibits much greater surface area and exceptional conductivity making it a potential candidate for different uses. Graphene has been reported in several applications such as a biosensors, 38 gas sensors, 8 electronic device design, 39 transistors, fuel cells, 40 photovoltaic devices, 41 photocatalytic hydrogen generation, etc.…”

Electrochemical surface reconstructed Ptx(x=2,3)Si/PtSi/p-Si photocathodes for achieving high efficiency in photoelectrochemical H2 generation

“…[5][6][7][8] Platinum (Pt) has been evidenced to be the most active hydrogen evolution reaction (HER) catalyst, 9 and would be an ideal candidate for modication of the Si-based photocathode. [10][11][12][13][14][15] However, the scarcity and high cost of Pt make it challenging for use in a large scale. Therefore, it is imperative to make the balance right in reducing the usage of Pt and achieving a high catalytic activity.…”

Fabrication of Semi-Transparent SrTaO2N Photoanodes with a GaN Underlayer Grown via Atomic Layer Deposition

“…10,11 While efficiencies have been improving over the past decades, enhanced sunlight utilization and circumvention from applying external voltage remain pressing issues, in addition to durability problems. [12][13][14][15][16] For the former, two fundamental losses are linked with the low photoabsorbance. On one hand, most of the photon energy is lost with incident photons possessing energy lower than the bandgap (Eg); on the other hand, photons containing higher energy in comparison to Eg, are partially wasted by emitting phonons.…”