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One of the major challenges in photocatalytic hydrogen production is to improve the separation efficiency of photo-generated carriers. Therefore, we prepared ZIS/BMO heterojunctions by hydrothermal method to promote the directional separation of photogenerated carriers. A series of characterization results show that the successful preparation of heterojunctions substantially increases the separation and transfer rate of photogenerated carriers. 11% ZIS/BMO had the highest photocatalytic hydrogen production performance reached 1502.6 μmol/g/h, which is 2.78 times than ZIS monomer. Simple construction of heterojunctions but dramatic improvement of photocatalytic hydrogen production performance opens up new horizons for photocatalyst modification. • A series of ZnIn 2 S 4 /Bi 2 MoO 6 heterojunction photocatalysts were prepared by a facile method. • The charge transfer and separation efficiency was enhanced. • A hydrogen production rate of 1502.6 μmol/g/h was achieved via this strategy. [ABSTRACT FROM AUTHOR]

Improving the separation efficiency of photo-generated electron–hole pair is a key issue in the field of photocatalytic hydrogen production. In this work, we successfully improved the efficiency of photo-generated carrier separation using the synergistic action of sulfur (S) vacancies and a Ni2P co-catalyst. Vs-Zn0.5Cd0.5S (Vs-ZCS) with S vacancies was designed and constructed, and Vs-ZCS/Ni2P photocatalysts were prepared with non-precious metal Ni2P as a co-catalyst. Among all the produced materials, Vs-ZCS/Ni2P-5% has a photocatalytic characteristic of 40.81 mmol g−1 h−1, which is 7.88, 3.08 and 3.75 times greater than those of ZCS (5.18 mmol g−1 h−1), Vs-ZCS (13.25 mmol g−1 h−1) and ZCS/Ni2P-5% (10.88 mmol g−1 h−1), respectively. The results of transient photo-current, electrochemical impedance spectroscopy, photoluminescence and time-resolved fluorescence show that the synergistic effect of S vacancies and Ni2P significantly promotes the separation and transfer efficiency of photo-generated carriers, as well as the photocatalytic hydrogen production reaction. Superoxide radicals and electrons are the active species for photocatalytic hydrogen generation, which is confirmed by active species capture tests and EPR. This study presents an innovative approach for developing photocatalysts with low cost and good catalytic performance. [ABSTRACT FROM AUTHOR]

Due to its low photogenerated carrier separation efficiency and wide band gap, the photocatalytic activity of TiO 2 is not ideal. In this work, CeCO 3 OH/TiO 2 composites were successfully prepared by a simple hydrothermal method. A series of characterisations shows that the CeCO 3 OH/TiO 2 composites improves the photogenerated carrier separation efficiency, narrowes the band gap width and increases the visible light absorption capacity compared with the monomer, enhancing the photocatalytic hydrogen evolution performance. Under visible light irradiation, 20% CeCO 3 OH/TiO 2 exhibites the highest photocatalytic hydrogen production performance of 2386.16 μmol g−1 h−1, which is 18.7 times higher than that of pure TiO 2 and 25.8 times higher than that of pure CeCO 3 OH. It provides ideas for the development of more efficient photocatalytic materials and technologies. • CeCO 3 OH loading on the TiO 2 surface promotes the separation of photogenerated carriers. • 20% CeCO 3 OH/TiO 2 has the best photocatalytic performance, which is 18.7 and 25.8 times higher than TiO 2 and CeCO 3 OH. • A possible mechanism for photocatalytic hydrogen production is proposed. [ABSTRACT FROM AUTHOR]

The application of metal catalysis has gained prominence as a study area in recent years. In this work, we use adsorptive reduction and calcination to create Au–Pd alloy catalysts on COCN-2 with varying metal loadings. The plasma resonance effect of the alloys increases the photoresponse of the catalysts, and the engineering of nitrogen defects strengthens the strong bonds between Au–Pd alloy particles and carbon nitride graphite, optimizing the electronic structure, encouraging electron-directed migration, and increasing the efficiency of the reduction reaction. As a result, the efficiency of hydrogen generation by the Au–Pd 0.6 /COCN-2 catalyst is 5.089 mmol g−1 h−1, which is 2367 times higher than that of the g-C 3 N 4 catalyst. Our findings highlight the crucial part that flaws play in strengthening the strong bonds that exist between the metal and the support, which enhances photocatalytic hydrogen generation. This work offers insightful information about creating effective photocatalysts. • A series of Au–Pd/COCN catalysts were prepared via a facile method. • The performance of Au–Pd 0.6 /COCN-2 reached 5.089 mmol g−1 h−1, which is 2367 times higher than the pristine g-C 3 N 4. • A series of investigations were conducted to reveal the mechanism. [ABSTRACT FROM AUTHOR]

Copper species have been extensively researched as effective cocatalysts for hydrogen evolution because of their inexpensive nature when compared to Pt. In this work, we have successfully loaded Cu nanoparticles highly dispersed on the surface of ZnIn 2 S 4 (ZIS) by an always simple low-temperature vacuum reduction method, which significantly improved the separation efficiency of photogenerated carriers. According to the transient photocurrent (TPR) and PL results, when the mass fraction of Cu is 0.6%, the maximum photocurrent density is approximately 0.55 μA/cm2, which is 2.75 times that of ZIS. And the separation efficiency of the photogenerated carriers is the fastest at this point. Simultaneously, under visible light and with a Cu loading of 0.6% in the Cu/ZnIn 2 S 4 (Cu/ZIS) composite material, the efficiency of hydrogen production is 6.56 times greater than that of pure ZIS, ultimately achieving an optimal value of 4.66 mmol/g/h. This study provides a new method for the preparation of photocatalysts with a high efficiency of electron-hole separation. [Display omitted] • Cu/ZIS improves electron-hole separation efficiency and spectral response range. • The photocatalytic hydrogen production reached 4.66 μmol−1h−1, which is 6.56 times that of pure ZIS. • A possible mechanism of photocatalytic hydrogen production is proposed. • A completely new method for low-temperature vacuum nonnoble metal deposition is proposed. [ABSTRACT FROM AUTHOR]

The high recombination rate of photogenerated electron-hole seriously affects the photocatalytic hydrogen production performance of TiO 2. Meanwhile, the lack of clarity of the active species in photocatalytic hydrogen production poses a certain obstacle for catalyst modification. To solve this problem, TiO 2 /SnIn 4 S 8 (TS) type II heterojunctions were prepared in this study, and TS composites achieve rapid separation and fast transfer of electron-hole. TPR results showed that the photocurrent of TS-10 increased from 2 μA/cm2 to 14 μA/cm2. In addition, the results of active species trapping experiments showed that the superoxide radicals (·O 2 -) were the main active species in the photocatalytic hydrogen production of TS-10. As a result, TiO 2 /SnIn 4 S 8 exhibited highly efficient photocatalytic hydrogen production performance. The hydrogen production rate of the optimal ratio of TS-10 reached 1603.47 μmolg-1h-1, which was 16 times higher than that of pure TiO 2 , and the apparent quantum efficiency (AQY) reached 2.064%. This study clarifies the active species in photocatalytic hydrogen evolution and provides new ideas for designing materials with high photocatalytic hydrogen evolution performance. • Effective reduction of electron-hole pair compounding efficiency. • It is clarified that ·O 2 - is the active species in the photocatalytic hydrogen production of TS composites. • The best photocatalytic H 2 performance is 1603.47 μmolg-1h-1, which was 16 times higher than pure TiO 2. [ABSTRACT FROM AUTHOR]

Photogenerated electron-hole separation and transfer and band gap modulation are the main reasons for the performance of semiconductor catalysts. These problems can be effectively solved by the proper use of co-catalysts. However, the current co-catalysts are generally noble metal co-catalysts, which cannot be used industrially because of their high cost. Therefore, it is important to use non-noble metal co-catalyst to solve these problems. In this study, MoO 2 with localized surface plasmon resonance (LSPR) effect loaded onto ZnIn 2 S 4 (ZIS) by primary hydrothermal method and structured to form type II heterojunctions. The formation of the heterojunctions not only tunes the band gap to improve the light absorption intensity, but also reduces the charge transfer resistance and promotes electron-hole directed movement to improve the electron-hole separation efficiency. The tuning of the band gap and the increase in the electron-hole separation rate lead to improved performance of all ZIS/MoO 2 heterojunctions under visible light (λ ≥ 420 nm). Among them, ZIS/MoO 2 -4% has the best photocatalytic performance of 2.757 mmol g−1 h−1, which is 3.75 times higher than that of pure ZIS (0.736 mmol g−1 h−1). This study provides a new strategy for the preparation of high performance catalysts without precious metals. • ZnIn 2 S 4 /MoO 2 was prepared by hydrothermal solvothermal method. • The best hydrogen production of ZnIn 2 S 4 /MoO 2 under visible light was 2.801 mmolg−1h−1. • ZnIn 2 S 4 /MoO 2 broadens the visible light response and enhances the electron-hole separation. [ABSTRACT FROM AUTHOR]

• A novel CdLa 2 S 4 /Ni 2 P catalyst with excellent photocatalytic H 2 evolution was introduced. • Catalyst with 15 % Ni 2 P dosage exhibited maximum photocatalytic H 2 evolution rate as 1.143 mmolh-1g−1, which was 10 times higher than that of pure CdLa 2 S 4. • The heterojunction structure formed by Ni 2 P and CdLa 2 S 4 improved the separation efficiency of photogenerated electron-hole pairs, thus prompted the H 2 evolution ability and the catalyst stability. Metal sulfides, often exhibited excellent photocatalytic H 2 evolution ability, has attracted more and more attention, whereas their industry applications were limited due to the photocorrosion. Therefore, the inhibition of photocorrosion is the key issue to promote the industrialization of metal sulfide catalysts. In this work, CdLa 2 S 4 /Ni 2 P catalysts with satisfactory H 2 evolution property were designed and synthesized. Catalyst with 15 % Ni 2 P dosage exhibited maximum photocatalytic H 2 evolution rate as 1.143 mmolh-1g−1, which was 10 times higher than that of pure CdLa 2 S 4. Such high catalytic efficiency maintained after 5 photocatalytic cycles. According to the results of transient photocurrent and photoluminescence, the heterojunction structure formed by Ni 2 P and CdLa 2 S 4 improved the separation efficiency of photogenerated electron-hole pairs, thus prompted the H 2 evolution ability and the catalyst stability. Further EPR results confirmed the existence of heterojunctions in the catalyst and proposed a possible reaction mechanism. The results show that the CdLa 2 S 4 /Ni 2 P composite photocatalyst has good visible light response and photochemical stability, and has broad application prospects in solar driven photocatalytic decomposition of water to hydrogen production. [ABSTRACT FROM AUTHOR]

One key challenge in photocatalytic hydrogen production is how to construct high-performance photocatalyst. Covalent triazine framework (CTF) based polymers as photocatalysts show great application potential because of their good photocatalytic activity, high chemical stability, tunable electronic and optical properties, and easy synthesis process. In this paper, we designed the ternary Z-scheme heterojunction Au@TiO 2 -X%TrTh based on CTF polymer TrTh, TiO 2 and Au nanoparticle, which exhibit higher photocatalytic hydrogen production rate compared with the corresponding binary heterojunction Au@TiO 2 and TiO 2 -12%TrTh. The results of photocatalytic hydrogen production show that the optimized Au@TiO 2 -12%TrTh has a remarkable hydrogen production rate of 4288.54 μmol g−1 h−1, which is about 312.3 times of Au@TiO 2 and 9.1 times of the TiO 2 -12%TrTh. The enhanced hydrogen production activity of the ternary heterojunction comes from the local surface plasmonic resonance effect of Au nanoparticle, lower recombination efficiency of photogenerated electron-holes pairs and Z-scheme electron transfer pathway of Au@TiO 2 -12%TrTh. The work provides a new strategy for designing efficient and practical photocatalyst. [Display omitted] • Ternary Au@TiO 2 -X%TrTh heterojunctions are prepared for hydrogen evolution. • The introduction of polymer TrTh extends the absorption of visible light of the composites. • The Au nanoparticles can accelerate the photoinduced carrier migration. • A Z-Scheme electron flow direction was purposed for the heterojunctions. • The ternary composites show excellent photocatalytic performances. [ABSTRACT FROM AUTHOR]

TiO 2 nanotube arrays (TiO 2 NTs) were regarded as the outstanding semiconductors for the photocatalytic application in waste water treatment and H 2 generation, and CdS nanoparticles as the visible light sensitizers were traditionally used to enhance the photocatalytic performance. In this paper, CdS–CuS co-sensitizers were deposited on TiO 2 NTs by one-pot hydrothermal method, and the Cu/Cd ratio was changed to adjust the hybrid photocatalyst composition and electron transfer. The photocatalytic data indicated that suitable CdS–CuS composition could effectively enhance the photocatalytic pollutant removal and photocurrent/H 2 evolution and the hybrid photocatalyst also exhibited the high stability by the inhibition of CdS photocorrosion. The p-n heterojunction construction of TiO 2 NTs/CdS–CuS benefited the solar response, photoelectron separation and photocatalytic reaction, and the photocatalytic mechanism and photoelectron transfer were investigated. The p-n heterojunctional photocatalyst is supposed to apply in environmental remediation and new energy development. [ABSTRACT FROM AUTHOR]

The high photogenerated electron-hole complexation rate has been the main reason limiting the practical application of carbon nitride, while the construction of heterojunction can promote the separation of photogenerated carriers, broaden the light absorption range and effectively improve its photocatalytic activity. Therefore, in this work, Cu 2 S was loaded onto g-C 3 N 4 nanosheets by in situ deposition, and a series of Cu 2 S/Nv-C 3 N 4 p-n heterojunctions were prepared by varying the loading amount of Cu 2 S. The photocatalytic performance test results showed that the best photocatalytic hydrogen production performance of 10% Cu 2 S/Nv-C 3 N 4 reached 197 μmolg−1h−1, which was 11.4 times that of pure Nv-C 3 N 4 and 47.5 times that of pure Cu 2 S. The enhanced photocatalytic activity is attributed to the formation of Cu 2 S/Nv-C 3 N 4 p-n heterojunction, which effectively promotes the separation and transfer of photogenerated electron-hole and enhances light absorption. This work constructs a novel type of C 3 N 4 heterojunction composite, which provides a new way to improve the photocatalytic hydrogen evolution performance of C 3 N 4. [Display omitted] • p-n heterojunction that promotes the separation of photogenerated electron-hole pairs and enhances light absorption. • The best performance reached 197 μmolg−1h−1, 11.4 times than pure Nv-C 3 N 4 and 47.5 times than pure Cu 2 S. • A possible mechanism of the photocatalytic hydrogen is proposed. [ABSTRACT FROM AUTHOR]

• NiO co-catalysts improve both electron-hole separation efficiency and light absorption intensity. • Optical catalytic hydrogen production up to 5 mmolg−1 h−1. • ZnIn 2 S 4 /NiO-3% has good stability, with only 2.4% drop in performance after 12 h of reaction. Photocatalytic hydrogen production is considered as a good countermeasure to solve the energy crisis, but the existing photocatalysts have very slow electron-hole separation efficiency. How to design a photocatalyst with high photogenerated carrier separation efficiency has become a difficult rproblem. The efficiency of photogenerated carrier separation can significantly improve by precious metal co-catalyst, but its further development is limited by high cost. In this work, non-precious metal NiO is used as a co-catalyst and formed heterojunction with ZnIn 2 S 4 (ZIS) as a cocatalyst, which significantly enhances the efficiencies of photogenerated carrier separation. According to the results of transient photocurrent (TPR) and Photoluminescence (PL), ZnIn 2 S 4 /NiO (ZIS/NiO) has the fastest photogenerated carrier separation rate when the mass fraction of NiO is 3%, which is about 5 times than pure ZIS. At the same time, the highest photocatalytic hydrogen production rate of 5 mmolg−1 h−1 was achieved under visible-light (λ ≥ 420 nm), which was 6.2 times more than pure ZIS (0.804 mmolg−1 h−1). This work offers a new option for low cost, high performance co-catalyst. [ABSTRACT FROM AUTHOR]

In this work, type II heterojunctions were constructed by in suit loading of ZnIn 2 S 4 (ZIS) nanosheets onto S-doped g-C 3 N 4 (SCN) nanosheets by a simple hydrothermal synthesis method. The formation of heterojunction induced rapid electron-hole separation, while the introduction of SCN reduced the internal resistance of photogenerated carriers to transfer. When the mass fraction of SCN was 20 %, the best photocatalytic hydrogen production performance was 1.63 mmol g−1 h−1 under visible light irradiation (λ > 420 nm), which was 7.7 and 2.8 times higher than SCN (0.21 mmol g−1 h−1) and ZIS (0.57 mmol g−1 h−1), respectively. The enhanced photocatalytic activity was mainly due to greater light utilization achieved by band gap adjustment through constructing heterojunctions and improved electron-hole separation efficiency. This method can effectively improve the photocatalytic performance of ZIS-based photocatalysts in a simple way. [Display omitted] • ZnIn 2 S 4 (ZIS) nanosheets were loaded in situ on S doped g-C 3 N 4 (SCN) nanosheets by a simple hydrothermal synthesis method. • Type II heterojunction can expand the light utilization and improve the electron-hole separation efficiency. • The best photocatalytic performance of 20%-SCN/ZIS heterojunction reached 1.63 mmol g−1 h−1 under visible-light irradiation. [ABSTRACT FROM AUTHOR]