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Heterogeneous catalysts possess many advantages over single-phase catalysts. However, how to tune the heterogeneous interface state and density in heterostructures to optimize their electrocatalytic performance is still a challenge. Here, we propose a method for the preparation of NiS–NiS 2 heterostructure by vulcanization of nickel foam at high temperature, which can effectively tune the weight ratio of NiS to NiS 2 in heterostructure and their corresponding electrocatalytic urea oxidation reaction (UOR), hydrogen evolution reaction (HER) and overall urea splitting performance. The electrocatalytic activity show a trend of volcano curve with the increase of the ratio of NiS to NiS 2 , and the best electrocatalytic activity was obtained at the ratio of 6.74, in which the potentials at current density of 10 mA cm−2 of UOR, HER and overall urea splitting are 1.28 V, −49.5 mV and 1.34 V versus reversible hydrogen electrode (vs. RHE), and the Tafel slopes are 21.7, 74.1 and 90.9 mV dec−1, respectively. Furthermore, it also demonstrates excellent electrocatalytic stability. This work provides an effective way to tune the interfacial structure of heterogeneous electrocatalysts while significantly improving their electrocatalytic performance, which is beneficial to the development of efficient heterostructure and expand their applications. [Display omitted] • NiS–NiS 2 heterostructures with adjustable ratio of NiS to NiS 2 were successfully synthesized by vulcanization of nickel foam. • The electrocatalytic activity of NiS–NiS 2 show a trend of volcano curve with the increase of the ratio of NiS to NiS 2. • The NiS–NiS 2 heterostructures reveal excellent electrocatalytic activity and stability for overall urea splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] Constructing photocatalytic materials into three-dimensionally ordered macroporous (3DOM) is considered an effective strategy for improving mass transfer behaviors and shortening the electron migration path. However, this strategy is challenging for ternary semiconductors because they cannot be directly synthesized by traditional thermal decomposition methods. Ternary systems need to face the structural instability caused by the construction of macroporous morphology, which limits the application of the ordered macroporous structure. In this work, we designed a novel and efficient two-step crystal nucleation strategy for constructing a highly stable ternary ordered macroporous structure. Here, 3DOM NaTaO 3 was reported as a promising candidate. Compared with nonporous NaTaO 3 , which has no catalytic activity in pure water, 807.9 and 280.1 μmol g−1h−1 of H 2 and H 2 O 2 production rates were first achieved on the 3DOM NaTaO 3. Furthermore, the rate of photocatalytic H 2 evolution over the 3DOM NaTaO 3 improved sharply to 3.9 mmol g−1h−1 in methanol aqueous solution, which was 139 times that of nonporous NaTaO 3. The construction of 3DOM NaTaO 3 enables the participation of the bulk interior in photochemical reaction and provides more options for later decoration. This work opens a new door for constructing more 3DOM ternary semiconductors for catalytic reactions. [ABSTRACT FROM AUTHOR]

ZnO-based photocatalysts have been widely applied to photocatalytic reactions. However, the pure phase ZnO is rarely used in degradation of refractory pollutants and photocatalytic hydrogen evolution due to its poor photo-redox ability. In this study, we develop a novel surface atom regulation strategy using fructose molecules containing hydroxyl groups to improve photo-oxidation ability of ZnO. Interestingly, the fructose-regulated ZnO nanosheets with oxygen vacancies exhibit more positive surface valence band maximum than that of pristine ZnO. The photogenerated holes with strong oxidation capacity can be formed on the fructose-regulated ZnO nanosheets. The fructose-regulated ZnO nanosheets can rapidly degrade high concentration of phenol and other organic pollutants, which is difficultly achieved by the pristine ZnO nanosheets. In addition, photocatalytic H 2 production activity is also found on our pure phase ZnO. This work provides a new design strategy for modifying the surface structure of photocatalysts to improve photocatalytic performance. [ABSTRACT FROM AUTHOR]

Solar energy utilization is a promising strategy for the photocatalytic generation of H 2 from water. Herein, a CuS-modified ZnO rod/reduced graphene oxide (rGO)/CdS heterostructure was fabricated via Cu-induced electrochemical growth with Zn powder at room temperature. The resulting powder revealed good interfacial bonding and promoted photoexcited carrier transport. The CuS nanoparticles played a pivotal role in enhancing visible-light responses and demonstrated excellent catalytic performance. A high visible-light photocatalytic H 2 generation rate of 1073 μmol h−1 g−1 was obtained from the CuS–ZnO/rGO/CdS heterostructure containing 0.23% CuS and 1.62% CdS. Increased photoexcited electron lifetimes, improved carrier transport rates, and decreased fluorescence intensities confirmed the synergistic effects of each of the components of the heterostructure. This study provides an innovative strategy for constructing multi-component heterostructures to achieve efficient visible-light H 2 evolution. Image 1 • A novel electrochemical growth strategy was developed to prepare CuS–ZnO/rGO/CdS. • A wide visible-light absorption band was introduced into the heterostructure. • CuS–ZnO/rGO/CdS exhibited an improved H 2 generation rate under visible light. [ABSTRACT FROM AUTHOR]

Hydrogen spillover is the key step during the CO 2 methanation process that provides active hydrogen species for hydrogenation and facilitates the reaction at lower temperatures. This work features the synthesis of CeO 2 -supported NiFe alloy catalysts, and the subsequent activation using plasma treatment (PT). The PT catalysts exhibit a considerable improvement in performance at low temperatures as compared to the calcined (untreated) catalysts. The considerable enhancement in catalytic properties could be appropriate to the abundant hydroxyl (OH−) groups and the great hydrogen spillover ability of the PT catalysts. Furthermore, temperature-programmed surface reduction (TPSR) was used to determine the hydrogenation and CH 4 generation temperatures and to reveal the promotion of PT catalysts. Formate was considered the key intermediate during the CO 2 methanation process according to the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results. [Display omitted] • Successfully synthesized PT-NiFe/CeO 2 catalysts by plasma treatment for CO 2 methanation. • The performances of PT-NiFe/CeO 2 catalysts were increased by the enhancement of hydrogen spillover and hydroxyl groups. • Understanding the promotion of hydrogen spillover by CO 2 + H 2 TPSR. • Revealing the hydrogenation mechanism by in-situ DRIFTS experiments. [ABSTRACT FROM AUTHOR]

ZnO sheets with short carrier transport distance are suitable for constructing heterostructures for improved photocatalytic hydrogen evolution activity. Narrow bandgap CdSe nanoparticles (NPs) can be used to sensitize the ZnO sheets and consequently extend the visible light response range. The ZnO-CdSe heterostructural sheets, synthesized through a light-assisted growth method, consisted of single-crystal ZnO sheets and CdSe NPs distributed on the surface of ZnO sheets. The ZnO-CdSe heterostructural sheets exhibited higher photocatalytic hydrogen rate than ZnO, CdSe, and ZnO particle-CdSe under light irradiation. The photocatalytic hydrogen evolution rates of the ZnO-CdSe heterostructural sheets were significantly improved under UV–visible and visible light ( λ  ≥ 420 nm) irradiations when Pt nanoparticles were loaded as cocatalysts. The heterostructural sheets also exhibited stable hydrogen generation rate in a long-term photocatalytic reaction. The synergistic effect between ZnO sheets and CdSe NPs and shortened transport distance of photoexcited carriers in the sheet-like heterostructure mainly contributed to the improved photocatalytic hydrogen activity. [ABSTRACT FROM AUTHOR]

Noble-metal-free semiconductor materials are widely used for photocatalytic hydrogen generation because of their low cost. ZnO-based heterostructures with synergistic effects exhibit an effective photocatalytic activity. In this work, NiO@Ni-ZnO/reduced graphene oxide (rGO)/CdS heterostructures are synthesized by a multi-step method. rGO nanosheets and CdS nanoparticles were introduced into the heterostructures via a redox reaction and light-assisted growth, respectively. A novel Ni-induced electrochemical growth method was developed to prepare ZnO rods from Zn powder. NiO@Ni-ZnO/rGO/CdS heterostructures with a wide visible-light absorption range exhibited highly photocatalytic hydrogen generation rates under UV–vis and visible light irradiation. The enhanced photocatalytic activity is attributed to the Ni nanoparticles that act as cocatalysts for capturing photoexcited electrons and the improved synergistic effect between ZnO and CdS due to the rGO nanosheets acting as photoexcited carrier transport channels. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution over semiconductors is an efficient method for solar-energy conversion. Heterostructural photocatalysts with separated photoexcited carriers exhibit efficient photocatalytic hydrogen evolution without co-catalysts. In this study, heterostructures comprising of Cd 1-x Zn x S and Zn 1-y Cd y S phases were prepared through the replacement and sulfuration process at high temperature using Zn powders as the precursor. Highly crystalline Cd 1-x Zn x S-Zn 1-y Cd y S heterostructures without noble metal co-catalysts present a stable and highly effective photocatalytic hydrogen evolution rate under both UV–visible and visible-light irradiations due to the synergistic effects of Cd 1-x Zn x S and Zn 1-y Cd y S. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) nanosheets are introduced to ZnS–CdS heterostructures to improve photocatalytic hydrogen generation. ZnS and CdS nanoparticles are formed on the surface of GO nanosheets via a light irradiation-assisted method. Here, GO construct a carrier transport channel between ZnS and CdS to enhance cooperative effects. The ZnS–CdS/GO heterostructures exhibit high photocatalytic hydrogen generation rates under either UV–visible or visible light irradiation. After loading of Pt nanoparticles as co-catalysts, the photocatalytic hydrogen generation rate of the proposed heterostructures is significantly improved to as high as 1.68 mmol h −1 under UV–visible light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-crystal ordered networks of Ta 2 O 5 was constructed by micro-terminal regulation. • Single-crystal ordered networks reduce carrier recombination rate at grain boundaries. • The SCON-Ta 2 O 5 exhibits a considerably improved photocatalytic H 2 evolution activity. The ordered macroporous structure of photocatalytic semiconductors can enable smooth mass transfer, high hydrogen release efficiency and multiple reaction site interfaces. Remote electronic communications and structural continuity are necessary to achieve these goals. The single-crystal ordered network structures are ideal candidates to meet the above requirements. However, fabricating such continuous single-crystal structures is very challenging due to the rapid formation of grain boundaries. In this study, highly ordered poly(methyl methacrylate) (PMMA) was chosen as hosts to build a nanoreactor. A micro-terminal was developed in nanoreactors to generate the suitable growth environment for single-crystal ordered networks of Ta 2 O 5 (SCON-Ta 2 O 5). By regulation of the nanoreactor space, the effect of mass transfer channel and carrier migration distance on the photocatalytic performance of SCON-Ta 2 O 5 was systematically investigated. A substantially improved photocatalytic hydrogen performance was realized on SCON-Ta 2 O 5. Thus, SCON-Ta 2 O 5 has a great potential in other applications and this general synthetic strategy could extend the possibility of macroporous single-crystal growth to other functional semiconductors. [ABSTRACT FROM AUTHOR]