One-step chemical vapor deposition of MoS₂ nanosheets on SiNWs as photocathodes for efficient and stable solar-driven hydrogen production

Abstract

Silicon nanowires (SiNWs) are widely used as photocathodes because of their large electrochemically available surface-area density and inherent ability to decouple light absorption from the transport of minority carriers. In order to minimize overpotential for solar-driven hydrogen (H) production, a combination of an ultrathin molybdenum disulfide (MoS) layer with SiNWs as photocathode has attracted much attention. Herein, for the first time, this study presents the synthesis of a composite photocathode via direct growth of ultrathin MoS nanosheets on SiNWs (referred to as SiNWs/MoS) by one-step chemical vapor deposition (CVD). Due to the high surface-area density of the arrays of SiNWs, the discontinuous MoS nanosheets grown on the SiNWs achieved a much higher density of active sites. Moreover, the coating of MoS on the SiNWs was found to protect the photocathode during the photoelectrochemical (PEC) reaction. A high efficiency with photocurrent j of 16.5 mA cm (at 0 V vs. reversible hydrogen electrode) and an excellent stability over 48 h of PEC operation were achieved under a simulated 1 sun irradiation.

Strategies for Semiconductor/Electrocatalyst Coupling toward Solar‐Driven Water Splitting

“…They found that the obtained Ag@Si/MoS 2 photocathode with optimized MoS 2 loading exhibited much improved PEC performance for HER, compared to the Ag@Si and MoS 2 ‐modified planar Si electrodes. Furthermore, the group reported the fabrication of SiNW photocathodes coupled with MoS 2 nanoflakes grown by a similar CVD procedure . Although the basal planes of MoS 2 were parallel to the NW axis so that the catalytically active edge sites were not preferentially exposed, the as‐synthesized SiNWs/MoS 2 photocathode still showed reasonably good PEC HER performance as compared to those reported in the literature (without buried junctions), with a photocurrent density of 16.5 mA cm −2 achieved at 0 V RHE and an impressive long‐term stability of 48 h in 0.5 m H 2 SO 4 .…”

“…Given the ease of CVD growth of Mo‐based catalysts and their decent catalytic performance for HER or OER, Mo‐based catalysts including MoS 2 , MoO 3 , MoS x Cl y , have been explored to couple with semiconductor photoelectrodes for PEC water splitting. Using CVD, Zhang et al deposited MoS 2 NSs on Ag@Si nanosphere array photocathodes, using MoO 3 and sulfur (S) powders as the reaction precursors .…”

“…While the CVD growth of MoS 2 usually happens at a relatively high temperature (e.g., above 500 °C), a low‐temperature CVD will be preferable and allow for the integration of catalysts without affecting the intrinsic properties of semiconductor light absorbers. Jin's group recently reported low‐temperature CVD growth of MoQ x Cl y (Q = S, Se), an emerging efficient HER catalyst .…”

Ion Beam Defect Engineering on ReS2/Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction

“…In the circuit, R s represents the overall series resistance of the circuit, CPE dp is the capacitance phase element for the depletion layer of semiconductor, R ct,dp is the charge transfer resistance in the depletion layer, CPE dl is the capacitance phase element for double layer at semiconductor/electrolyte interface, and R ct,dl is the charge transfer resistance of double layer at semiconductor/electrolyte interface . According to previous work, the second semicircle on right yields of R ct,dl usually reflects the HER catalytic activity with a smaller value corresponding to a faster reaction rate. The inset histogram in Figure d reveals remarkable decreases of R ct,dl for all ReS 2 /Si photocathodes.…”

Bifunctional Electrocatalyst with 0D/2D Heterostructure for Highly Efficient Hydrogen and Oxygen Generation

“…It is worth noting that the impedance value is mainly caused by the electrolyte, and the change of the arc radius depends on the structure of the electrocatalyst. [32] Accordingly, the charge-transfer resistance (R ct ) of MoS 2 QDs/CoSe 2 hybrid is 15.4 Ω, which is much smaller than that of the CoSe 2 NSs (21.5 Ω) and MoS 2 QDs (225.6 Ω). At the same time, the Nyquist plots and the charge-transfer resistance (R ct ) values were fitted by a modified Randel model equivalent circuit ( Figure S4)".…”