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In this work, energy converters, which contain a GaP–Si heterojunction and Si-based Schottky barrier diodes with Al, Ti, Ag, and W, are used to convert 2 μm-thick 63Ni radioactive source energy into electrical energy. First, energy deposition distributions of the 63Ni radioactive source in these converters are simulated by using the Monte Carlo method. Then, the electrical output properties of the 63Ni/GaP–Si cell and 63Ni/metal–Si cell are determined through the numerical calculation. For the 63Ni/GaP–Si cell, with the optimized thickness of the GaP layer and doping concentration of Si, the maximum output power density and the conversion efficiency are 0.189 µW cm−2 and 1.83%, respectively. For the Si-based Schottky barrier cells with Al, Ti, Ag, and W, the 63Ni/Al–Si cell has the best electrical output properties with the same thickness of the metal layer and doping concentration of Si. When the thickness of metal Al is 0.1 µm and the doping concentration Na is 1 × 1013 cm−3, the maximum output power density and the conversion efficiency are 0.121 µW cm−2 and 1.18%, respectively. The calculation results indicate that the 63Ni/GaP–Si battery has better electrical output properties than the 63Ni/Al–Si Schottky battery. These results are valuable for fabricating practical batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing cost-effective cocatalyst-modified photocatalytic systems with boosted carrier separation and rapid surface catalytic reaction is an ideal strategy for effectively converting solar energy into desired fuels. Herein, a series of Cu 7 S 4 /Mn 0.3 Cd 0.7 S hierarchical heterostructures are designed and fabricated to achieve efficient and robust photocatalytic H 2 evolution by coupling one-dimensional (1D) Mn 0.3 Cd 0.7 S nanorods with two-dimensional (2D) Cu 7 S 4 nanosheets through a facile sonochemical strategy. Benefiting from dimensionality and cocatalyst effects, the constructed 2D/1D Cu 7 S 4 /Mn 0.3 Cd 0.7 S heterojunction photocatalyst containing 1.5 wt% Cu 7 S 4 displays excellent photostability and superior photocatalytic H 2 evolution rate up to 914.3 μmol h−1, which is 4.43 and 2.22-folds increment relative to bare Mn 0.3 Cd 0.7 S and the 3 wt% Pt/Mn 0.3 Cd 0.7 S, respectively. The various characterization results reveal that the utilization of semimetallic Cu 7 S 4 nanosheets as the cocatalyst to form a Schottky heterojunction can promote the light-harvesting capability, suppress charge carrier recombination, and provide sufficient reaction sites for hydrogen generation, thereby resulting in the dramatically improved photocatalytic performance. This work clarifies the role of Cu 7 S 4 nanosheets as the robust and cost-effective cocatalyst in the photocatalytic reaction and opens a new horizon for designing other Cu 7 S 4 -based cocatalyst/semiconductor Schottky heterostructures for efficient solar-to-fuel conversion. [ABSTRACT FROM AUTHOR]

The rational design of hierarchical heterojunction photocatalysts with efficient spatial charge separation remains an intense challenge in hydrogen generation from photocatalytic water splitting. Herein, a noble-metal-free MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 ternary heterostructure with a hierarchical flower-like architecture was developed by in situ growth of 3D flower-like ZnIn 2 S 4 nanospheres on 2D MoS 2 and 2D g-C 3 N 4 nanosheets. Benefiting from the favorable 2D-2D-3D hierarchical heterojunction structure, the resultant MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 nanocomposite loaded with 3 wt% g-C 3 N 4 and 1.5 wt% MoS 2 displayed the optimal hydrogen evolution activity (6291 μmol g−1 h−1), which was a 6.96-fold and 2.54-fold enhancement compared to bare ZnIn 2 S 4 and binary g-C 3 N 4 /ZnIn 2 S 4 , respectively. Structural characterizations reveal that the significantly boosted photoactivity is closely associated with the multichannel charge transfer among ZnIn 2 S 4 , MoS 2 , and g-C 3 N 4 components with suitable band-edge alignments in the composites, where the photogenerated electrons migrate from g-C 3 N 4 to ZnIn 2 S 4 and MoS 2 through the intimate heterojunction interfaces, thus enabling efficient electron-hole separation and high photoactivity for hydrogen evolution. In addition, the introduction of MoS 2 nanosheets highly benefits the improved light-harvesting capacity and the reduced H 2 -evolution overpotential, further promoting the photocatalytic H 2 -evolution performance. Moreover, the MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 ternary heterostructure possesses prominent stability during the photoreaction process owing to the migration of photoinduced holes from ZnIn 2 S 4 to g-C 3 N 4 , which is deemed to be central to practical applications in solar hydrogen production. [ABSTRACT FROM AUTHOR]

Exploring efficient and robust photocatalysts for solar hydrogen generation from water reduction is great significant in solving the energy shortage and environment contamination simultaneously. Herein, benefiting from the matchable energy band structures and band bending, the direct Z-scheme ZnIn 2 S 4 /NiWO 4 heterojunctions were successfully constructed by anchoring p-type NiWO 4 nanoparticles onto n-type ZnIn 2 S 4 nanosheets through a facile sonochemical route. By carefully regulating the interfacial structure, the optimized ZnIn 2 S 4 /NiWO 4 heterostructure without any cocatalyst displays excellent stability and remarkably improved photocatalytic hydrogen evolution activity (16.3 mmol∙g−1∙h−1), more 3.57-folds increment than bare ZnIn 2 S 4 photocatalyst. Mechanistic characterizations demonstrate that the dramatically boosted photocatalytic performance mainly results from the constructed Z-scheme heterostructure and intimately interfacial contact between ZnIn 2 S 4 and NiWO 4 , which results in the valid interfacial charge transfer channels, powerful redox potential and reduced hydrogen evolution energy barrier, as confirmed by the joint analysis of electron spin resonance (ESR) and photoelectrochemical measurements. More importantly, the photoinduced holes of ZnIn 2 S 4 are rapidly and effectively consumed in the unique Z-scheme charge transfer channels, which greatly favors the suppression of the photocorrosion caused by insufficient hole extraction during the photocatalytic reaction, thereby promoting the overall stability and reusability of the ZnIn 2 S 4 /NiWO 4 composite photocatalyst. This study paves the way for constructing other Z-scheme nano-heterostructure consisting of p-type and n-type semiconductors with efficient photoactivity and robust stability for energy and environmental applications. [Display omitted] • Z-scheme heterojunction consisting of p-type and n-type semiconductors was designed. • Mechanism for the enhanced photoactivity over ZnIn 2 S 4 /NiWO 4 heterojunction discussed. • High H 2 -production rate achieved over heterojunction, 3.57-fold higher than ZnIn 2 S 4. [ABSTRACT FROM AUTHOR]