Nickel nanoparticle-activated MoS₂for efficient visible light photocatalytic hydrogen evolution

Abstract

Direct sunlight-induced water splitting for photocatalytic hydrogen evolution is the dream for an ultimate clean energy source.

Unraveling Compensation between Electron Transfer and Strain in Ni-Ag-Mos2 Photocatalyst

“…Despite the importance, study of the interfacial contact between the layered semiconductor and hetero-junctional sites is not an easy task. As per the previous report, metallic contact between MoS 2 and Ni NP happens via Au [9] / Ag [10] nanobuffers as inferred from X-ray absorption (XA)-photoelectron emission microscopy (PEEM), referred to as X-PEEM, a spectromicroscopic full-field, synchrotron-based surface sensitive technique. The high sensitivity of the XA spectrum (XAS) to oxidization states, local structure, and electronic structure makes X-PEEM highly attractive technique.…”

“…2 and 3. In fact, the lattice of Ag (1 1 1) buffer well matches the one of the MoS 2 , providing a metallic contact between the metal and semiconductor [10]. In the second case, the silver is involved in bonding the Ni NPs and the atoms at the MoS 2 edge.…”

“…8b following the spectro-microscopic determinations. The figure adopts the work functions of 5.35 eV, 4.74 eV, and 5.20 eV for Ni, Ag and MoS 2 , respectively, [10,29] and the metal-semiconductor (M/S) contact model of metal-induced gap state [30]. Therein, the interface dipole was formed by the charge transfer across the bonds at the M/S interfaces.…”

“…In the former case, the product gets easily dissolved and emits oxygen under vigorous stirring and light irradiations. The latter one results the increase of the nickel hydroxides along with the native oxides [10] which indeed benefits the oxygen evolution reactions [35]. "…”

“…It's worth noting HER is mainly investigated here and the full water splitting requires dedicated instrumental setups and calibrations along with spectromicroscopic investigations of OER reactive sites to deduce mechanisms. However, a recent work of the similar system [10] showed the oxygen evolution is accompanied with the HER, denoting a full water splitting capability of the MAN system. Beside the same composites, the fraction of Ni used here falls into the range of the MAN system studied previously.…”