Metal-Semiconductor Heterojunction with Ohmic Contact Realizes Efficient Infrared-Light-Driven Photocatalysis

Efficient utilization of solar energy for photocatalytic applications, particularly in the infrared spectrum, is crucial for addressing environmental challenges and energy scarcity. Herein we present a general strategy for constructing efficient infrared-driven photocatalysts in a metal/semiconductor heterojunction with Ohmic contact, where metals with low work function as the infrared-light absorber and semiconductors with electron storage ability can overcome the unfavorable electron flowback. Taking the NixB/MO2 (M = Ce, Ti, Sn, Ge, Zr, etc.) heterojunction as an example, both experimental and theoretical investigations reveal that the formation of an Ohmic contact facilitates the transfer of hot electrons from NixB to MO2, which are stored by the ion redox pairs for the variable valence character of M. As expected, the heterojunction exhibits remarkable photocatalytic activity under infrared light (λ ≥ 800 nm), as evidenced by the efficient photofixation of CO2 to high-value-added cyclic carbonates. This study offers a general platform for designing infrared-light-driven photocatalysts.

Strategy of Graphdiyne (g-Cn H2n-2 ) Preparation Coupling with the Flower-Like NiAl-LDH Heterojunctions for Efficient Photocatalytic Hydrogen Evolution*

Graphdiyne (g-C_n H_2n-2 ), a novel two-dimension carbon allotrope material composed of a sp- and sp² -hybrid carbon network, has been widely explored since it was synthesized for the first time by Li's group in 2010. A series distinct and excellent properties bestow graphdiyne excellent performance in many fields. Here, an innovative progress for preparing graphdiyne by using Cu⁺ contained material as catalyst is reported and the composite CuI-GD is coupled with flower-like NiAl-LDH to produce H₂ from photocatalytic water splitting. The results of FTIR and Raman spectroscopy together reveal that graphdiyne nanosheets are synthesized successfully by employing a cross-coupling method. Photocatalytic hydrogen evolution performance shows that the hydrogen production activity of CuI-GD/NiAl-LDH has a 15- and 216-fold enhancement compared with CuI-GD and NiAl-LDH, respectively. A series of characterizations are carried out to expound the underlying reasons in the enhancement of the photocatalytic hydrogen production performance of CuI-GD/NiAl-LDH. Meanwhile, a possible mechanism for the photocatalytic hydrogen evolution process was proposed to understand the interaction among these materials.

Hot injection-induced synthesis of ZnCdS-rGO/MoS2 heterostructures for efficient hydrogen production and CO2 photoreduction

A highly efficient hybrid ZnCdS-rGO/MoS₂ heterostructure is successfully synthesized through a hot injection method and control loading of rGO/MoS₂. The synergism provides an unprecedently high H₂-generation rate of 193.4 mmol H₂ g^-1 h^-1 from water under full arc solar radiation and MeOH production (5.26 mmol g^-1 h^-1, AQY of 14.6% at λ = 420 ± 20 nm) from CO₂ reduction.

Graphdiyne Based Ternary GD-CuI-NiTiO3 S-Scheme Heterjunction Photocatalyst for Hydrogen Evolution

As the demand of fossil fuels continues to expand, hydrogen energy is considered a promising alternative energy. In this work, the NiTiO₃-CuI-GD ternary system was successfully constructed based on morphology modulation and energy band structure design. First, the one-pot method was used to cleverly embed the cubes CuI in the stacked graphdiyne (GD) to prepare the hybrid CuI-GD, and CuI-GD was anchored on the surface of NiTiO₃ by simple physical stirring. The unique spatial arrangement of the composite catalyst was utilized to improve the hydrogen production activity under light. Second, to combine various characterization tools and energy band structures, we proposed an step-scheme (S-scheme) heterojunction photocatalytic reaction mechanism, among them, the tubular NiTiO₃ formed by the self-assembled of nanoparticles provided sufficient sites for the anchoring of CuI-GD, and the thin layer GD acted as an electron acceptor to capture a large number of electrons with the help of the conjugated carbon network; cubes CuI could consume holes in the reaction system; the loading of CuI-GD greatly improved the oxidation and reduction ability of the whole catalytic system. The S-scheme heterojunction accelerated the transfer of carriers and improved the separation efficiency. The experiment provides a new insight into the construction of an efficient and eco-friendly multicatalytic system.

Zn0.8Cd0.2S Hollow Spheres with a Highly Dispersed Ni Dopant for Boosting Photocatalytic Hydrogen Generation

Facilitating charge separation and increasing surface active sites have always been the goals of photocatalysis. Herein, we synthesized a Ni-doped Zn_0.8Cd_0.2S hollow sphere photocatalyst with a facile one-step hydrothermal method. Energy-dispersive spectroscopy mapping showed the high dispersion of Ni ions in the Zn_0.8Cd_0.2S hollow spheres. The experimental results confirmed that Ni doping reduced the band structure of the substrate, suppressed the recombination of photo-induced electrons and holes, and provided more reactive sites. Therefore, the photocatalytic activity had been greatly improved. As a consequence, the detected photocatalytic H₂ evolution rate increased up to 33.81 mmol·h^-1·g^-1 over an optimal Ni doping (5 wt %) of Zn_0.8Cd_0.2S hollow spheres, which was 20.87-fold higher than that of pure CdS. Elemental mapping showed that the Zn element was mainly distributed in the outermost layer of the hollow spheres; this might be the critical factor that enabled Ni-doped Zn _x Cd_1-x S to maintain excellent stability.

Polytype wurtzite-nH ZnS (n = 2 and 8): facile synthesis and photocatalytic hydrogen production under sacrificial reagents

Zinc sulfide, as an excellent catalyst, has attracted a lot of attention from scholars owing to its photocatalytic hydrogen evolution from water splitting in the ultraviolet (UV) region.

Ni-MOF-74 derived nickel phosphide and In2O3 form S-scheme heterojunction for efficient hydrogen evolution

The composite structure of Ni2P/In2O3 constructs an S-scheme heterojunction that transfers useless electrons and holes to the composite interface for consumption.The loading of In2O3 further increases the photocatalytic hydrogen production activity.

Efficient photocatalytic hydrogen production by Mn0.05Cd0.95S nanoparticles anchored on cubic NiSe2

In the field of catalysis, three critical factors for evaluating catalyst activity include charge separation efficiency, photoabsorption, and surface activity sites.