Black Si Photocathode with a Conformal and Amorphous MoS_x Catalytic Layer Grown Using Atomic Layer Deposition for Photoelectrochemical Hydrogen Evolution

Abstract

We demonstrated how the photoelectrochemical (PEC) performance was enhanced by conformal deposition of an amorphous molybdenum sulfide (a-MoS x ) thin film on a nanostructured surface of black Si using atomic layer deposition (ALD). The a-MoS x is found to predominantly consist of an octahedral structure (S-deficient metallic phase) that exhibits high electrocatalytic activity for the hydrogen evolution reaction with a Tafel slope of 41 mV/dec in an acid electrolyte. The a-MoS x has a smaller work function (4.0 eV) than that of crystalline 2H-MoS2 (4.5 eV), which induces larger energy band bending at the p-Si surface, thereby facilitating interface charge transfer. These features enabled us to achieve an outstanding kinetic overpotential of ∼0.2 V at 10 mA/cm2 and an onset potential of 0.27 V at 1 mA/cm2. Furthermore, the a-MoS x layer provides superior protection against corrosion of the Si surface, enabling long-term PEC operation of more than 50 h while maintaining 87% or more performance. This work highlights the remarkable advantages of the ALD a-MoS x layer and leads to a breakthrough in the architectural design of PEC cells to ensure both high performance and stability.

Boosting Hydrogen Evolution Electrocatalysis via Regulating the Electronic Structure in a Crystalline–Amorphous CoP/CeOx p–n Heterojunction

“…This amorphous feature can also be consolidated by the XRD result of the contrast bare CeO x (Figure S6). This amorphous structure would enrich the interface and provide the flexibility to facilitate the transfer of electrons between CoP and CeO x , thus modulating the electronic structure of CoP and accelerating the HER …”

“…This amorphous structure would enrich the interface and provide the flexibility to facilitate the transfer of electrons between CoP and CeO x , thus modulating the electronic structure of CoP and accelerating the HER. 36 The chemical state and electronic interactions of CoP/CeO x are further investigated using XPS. In the XPS survey spectrum of CoP/CeO x -20:1 (Figure 4a), the signals of C, O, Co, P, and Ce can be detected, confirming the successful fabrication of heterojunction.…”

Interfacial engineering of a multijunctional In2O3/WO3@Ti4N3Tx S-scheme photocatalyst with enhanced photoelectrochemical properties

“…A smaller arc radius shows an efficient charge transfer and a more effective separation of photoinduced charge carriers. 47 As shown in Fig. 8c, pristine WO 3 and In 2 O 3 photocatalysts exhibited largest curves, an indication of a high charge transfer resistance, 41.2 and 42.3 Ω, respectively, attributed to the lower interfacial charge transfer and increased charge carrier recombination rate.…”

Efficient solar fuel production enabled by an iodide oxidation reaction on atomic layer deposited MoS2

“…The adsorption of intermediates (I*, O*, OH*, and OOH*) on the T1 termination was examined to determine the IOR and OER activity, as shown in Figure . The basal planes of 2H‐MoS 2 were excluded due to their chemical inertness 16,48–51 . Figure 3C shows the Gibbs free‐energy diagram of IOR for T1 termination of 2H‐MoS 2 , indicating the considerably low overpotential of 0.26 eV for the adsorption of iodine intermediates (Δ G I* ).…”

“…The basal planes of 2H-MoS 2 were excluded due to their chemical inertness. 16,[48][49][50][51] Figure 3C shows the Gibbs free-energy diagram of IOR for T1 termination of 2H-MoS 2 , indicating the considerably low overpotential of 0.26 eV for the adsorption of iodine intermediates (ΔG I* ). The low energy barrier can enable superior intrinsic IOR capability of 2H-MoS 2 , leading to facile adsorption of iodide and prompt desorption of iodine on the surface of 2H-MoS 2 .…”