Supporting Ultrathin ZnIn₂S₄ Nanosheets on Co/N‐Doped Graphitic Carbon Nanocages for Efficient Photocatalytic H₂ Generation

Abstract

Graphitic carbon materials are widely used to composite with semiconductors to promote photocatalytic activity, [21][22][23] because of their high conductivity and superb electron mobility for directing the movement of charge carriers. Moreover, N-doping is believed to further strengthen the electronic and chemical features of carbonaceous materials to enhance photocatalytic efficiency. [22] On the other hand, cobalt species with smart electron-mediating ability are favorite moieties to make catalysts for photoredox reactions. [24][25][26] In particular, carbon-confined Co nanoparticles (NPs) have considerable potential for water splitting catalysis. [27,28] Besides tuning chemical compositions, designing proper structures for photocatalysts also strongly influences the catalytic performance.Hollow structures are attracting intensive attention in various photocatalytic fields. [29] Hollow photocatalysts possess large surface area and plentiful reactive sites to enhance adsorption of reactants and boost surface-related redox reactions. [29,30] Meanwhile, the thin-shelled configuration of hollow scaffolds reduces charge diffusion length to assist separation and migration of electron-hole pairs. [31] Furthermore, hollow particles, especially polyhedral cages, [32] can enable reinforced utilization of solar energy by the reflection/scattering effect inside the cavity. [33] Therefore, integrating all the aforementioned thoughts into one photocatalyst design is expected to achieve high efficiency for solar-driven H 2 production.Herein, we grow ultrathin ZnIn 2 S 4 NSs on Co/NGC nanocages with embedded Co NPs surrounded by a few-layered NGC shell to construct hierarchical Co/NGC@ZnIn 2 S 4 (Co/NGC@ZIS) hollow heterostructures for photocatalytic water splitting to produce H 2 . As illustrated in Figure 1, fabrication of the hierarchical hollow composites starts with zeolitic imidazolate framework-8 (ZIF-8) polyhedrons as the precursor to produce core-shell ZIF-8@ZIF-67 dodecahedrons through an in situ solution growth method. Then, the ZIF-8@ZIF-67 particles are treated by high-temperature pyrolysis and acid leaching, generating the Co/NGC nanocages. At last, ultrathin ZnI 2 S 4 NSs are successfully grown on these Co/NGC nano cages to create hierarchical Co/NGC@ZIS cages. The catalytic functions of isolated Co NPs, conductive NGC and layered ZnIn 2 S 4 are integrated into hierarchical hollow structures with tightly Ultrathin ZnIn 2 S 4 nanosheets (NSs) are grown on Co/N-doped graphitic carbon (NGC) nanocages, composed of Co nanoparticles surrounded by few-layered NGC, to obtain hierarchical Co/NGC@ZnIn 2 S 4 hollow heterostructures for photocatalytic H 2 generation with visible light. The photoredox functions of discrete Co, conductive NGC, and ZnIn 2 S 4 NSs are precisely combined into hierarchical composite cages possessing strongly hybridized shell and ultrathin layered substructures. Such structural and compositional virtues can expedite charge separation and mobility, offer large surface area and abundant reactive si...

Construction of Hierarchical Hollow Co9S8/ZnIn2S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

“…[5] However, the photocatalytic performance of pure ZnIn 2 S 4 remains unsatisfactory, mainly because of the rapid recombination rate of the photogenerated electrons (e À )a nd holes (h + ). [6] Multiple previous studies have shown that the construction of aheterojunction with another appropriate metal sulfide semiconductor is an effective approach to enhance photoabsorption and improve the photocatalytic activity of ZnIn 2 S 4 photocatalysts. [4b,5a, 7] As an oble-metal-free cobalt sulfide photocatalyst, Co 9 S 8 has many advantages including its narrow band gap (0.9-1.4 eV), high conduction-band position, and efficient charge transfer.…”

Dispersed Nickel Cobalt Oxyphosphide Nanoparticles Confined in Multichannel Hollow Carbon Fibers for Photocatalytic CO2 Reduction

“…[23,24] In addition, hollow structured photocatalysts could utilize the sunlight more efficiently because of the reflection and scattering effects in the interior void. [22,[25][26][27] Although ah andful of single metal phosphides have shown the opportunity for photocatalytic CO 2 reduction reactions, [28][29][30] the application of mixed metal oxyphosphides with tailored structures and compositions in reductive CO 2 photoconversion is still much less reported. Herein, we demonstrate the design and synthesis of nickel cobalt oxyphosphide NPs (NiCoOP NPs) confined in multichannel hollow carbon fibers (MHCFs) for efficient photochemical CO 2 reduction with visible light.…”

Dispersed Nickel Cobalt Oxyphosphide Nanoparticles Confined in Multichannel Hollow Carbon Fibers for Photocatalytic CO2 Reduction

“…Moreover, the thin‐shelled topologies of hollow scaffolds will facilitate the separation and migration of light‐excited charges owing to the reduced diffusion distance from bulk to the surface . In addition, hollow structured photocatalysts could utilize the sunlight more efficiently because of the reflection and scattering effects in the interior void …”