Daochuan Jiang

A cocatalyst-free CdS nanorod/ZnS nanoparticle composite for high-performance visible-light-driven hydrogen production from water

Highly efficient, visible-light-induced hydrogen (H2) production via water splitting can be achieved without the help of a cocatalyst by using a noble-metal-free core–shell photocatalyst, in which zinc sulfide (ZnS) nanoparticles as the protective shell are anchored on the surface of cadmium sulfide nanorods (CdS NRs). Due to the close interfacial contact of component semiconductors, the electronic structure of CdS is strongly coupled with that of ZnS nanoparticles, leading to efficient transfer of charge carriers between them and the improvement of the CdS photostability. The CdS/ZnS NR photocatalyst showed much higher catalytic activity for H2 production than CdS NRs and ZnS under visible light irradiation (λ > 420 nm), which is probably due to fast transfer of the photogenerated charge carriers and/or electron tunneling in the one-dimensional core–shell nanorod structure. Under optimal conditions, the highest hydrogen evolution rate reached 239 μmol h−1 mg−1, which is much greater than ZnS and CdS NRs and also among the best cocatalyst-free photocatalysts for H2 production. The average apparent quantum yield can be achieved as ∼16.8% after 8 h of irradiation (monochromatic light at 420 nm ± 5 nm). A possible mechanism for the photocatalytic reaction based on CdS/ZnS NRs is also discussed.

Highly Efficient and Stable Water-Oxidation Electrocatalysis with a Very Low Overpotential using FeNiP Substitutional-Solid-Solution Nanoplate Arrays

The development of efficient water-oxidation electrocatalysts based on inexpensive and earth-abundant materials is significant to enable water splitting as a future renewable energy source. Herein, the synthesis of novel FeNiP solid-solution nanoplate (FeNiP-NP) arrays and their use as an active catalyst for high-performance water-oxidation catalysis are reported. The as-prepared FeNiP-NP catalyst on a 3D nickel foam substrate exhibits excellent electrochemical performance with a very low overpotential of only 180 mV to reach a current density of 10 mA cm-2 and an onset overpotential of 120 mV in 1.0 m KOH for the oxygen evolution reaction (OER). The slope of the Tafel plot is as low as 76.0 mV dec-1 . Furthermore, the long-term electrochemical stability of the FeNiP-NP electrode is investigated by cyclic voltammetry (CV) at 1.10-1.55 V versus reversible hydrogen electrode (RHE), demonstrating very stable performance with negligible loss in activity after 1000 CV cycles. This present FeNiP-NP solid solution is thought to represent the best OER catalytic activity among the non-noble metal catalysts reported so far.

Integrating noble-metal-free NiS cocatalyst with a semiconductor heterojunction composite for efficient photocatalytic H 2 production in water under visible light

Abstract Photocatalytic water splitting is an economical and sustainable pathway to use solar energy for large-scale H2 production. We report a highly efficient noble-metal-free photocatalyst formed by integrating amorphous NiS with a CdS nanorods (NRs)/ZnS heterojunction material for photocatalytic H2 production in water under visible light irradiation (λ

Cobalt nitride as an efficient cocatalyst on CdS nanorods for enhanced photocatalytic hydrogen production in water

Photocatalytic splitting of water to hydrogen (H2) has attracted much attention because of its potential to address the concerns of air pollution and energy shortage. In this present study, we report that noble-metal-free cobalt nitride (Co3N) can be used as an efficient cocatalyst on CdS nanorods (CdS NRs) for photocatalytic H2 production in water under visible light irradiation. Photoluminescence (PL) spectra and photoelectrochemical measurements indicated that the loading of Co3N onto CdS NRs can facilitate the separation and transfer of photogenerated charge carriers, leading to an enhanced photocatalytic activity for H2 production. The H2 production rate reached ∼137.33 μmol h−1 mg−1 (λ > 420 nm) and the apparent quantum yield (AQY) was ∼14.9% at 450 nm.

Synergistic Effect of a Molecular Cocatalyst and a Heterojunction in a 1 D Semiconductor Photocatalyst for Robust and Highly Efficient Solar Hydrogen Production

Photocatalytic production of hydrogen by water splitting is a promising pathway for the conversion of solar energy into chemical energy. However, the photocatalytic conversion efficiency is often limited by the sluggish transfer of the photogenerated charge carriers, charge recombination, and subsequent slow catalytic reactions. Herein, we report a highly active noble-metal-free photocatalytic system for hydrogen production in water. The system contains a water-soluble nickel complex as a molecular cocatalyst and zinc sulfide on 1D cadmium sulfide as the heterojunction photocatalyst. The complex can efficiently transport photogenerated electrons and holes over a heterojunction photocatalyst to hamper charge recombination, leading to highly improved catalytic efficiency and durability of a heterojunction photocatalyst- molecular cocatalyst system. The results show that under optimal conditions, the average apparent quantum yield was approximately 58.3 % after 7 h of irradiation with monochromatic 420 nm light. In contrast, the value is only 16.8 % if the molecular cocatalyst is absent. Such a remarkable performance in a molecular cocatalyst-based photocatalytic system without any noble metal loading has, to the best of our knowledge, not been reported to date.

An iron porphyrin-based conjugated network wrapped around carbon nanotubes as a noble-metal-free electrocatalyst for efficient oxygen reduction reaction

Developing an efficient, robust, and noble-metal-free catalyst for the oxygen reduction reaction (ORR) is crucial for the large-scale commercialization of fuel cells and metal–air batteries. Herein, we report a structurally well-defined iron porphyrin-based conjugated network on carbon nanotubes ((FeP)n-CNTs) as a novel electrocatalyst for the ORR. Its superior electrocatalytic activity toward the ORR is demonstrated by the high-performance catalytic activity of (FeP)n-CNTs with a positive ORR onset potential and half-wave potential (E1/2 ∼ 0.76 V vs. RHE) values as well as outstanding durability and methanol tolerance in alkaline media. In addition, the low H2O2 yield illustrates that the ORR occurs mainly via the direct four-electron (4e−) pathway, and testing shows that the small amount of produced H2O2 can be rapidly consumed through both electrochemical reduction and oxidation. Our results demonstrate that the as-prepared (FeP)n-CNT catalyst is a promising noble-metal-free catalyst for potential applications in fuel cells and metal–air batteries.

Stabilizing black phosphorus nanosheets via edge-selective bonding of sacrificial C 60 molecules

Few-layer black phosphorus (BP) with an anisotropic two-dimensional (2D)-layered structure shows potential applications in photoelectric conversion and photocatalysis, but is easily oxidized under ambient condition preferentially at its edge sites. Improving the ambient stability of BP nanosheets has been fulfilled by chemical functionalization, however this functionalization is typically non-selective. Here we show that edge-selective functionalization of BP nanosheets by covalently bonding stable C60 molecules leads to its significant stability improvement. Owing to the high stability of the hydrophobic C60 molecule, C60 functions as a sacrificial shield and effectively protects BP nanosheets from oxidation under ambient condition. C60 bonding leads to a rapid photoinduced electron transfer from BP to C60, affording enhanced photoelectrochemical and photocatalytic activities. The selective passivation of the reactive edge sites of BP nanosheets by sacrificial C60 molecules paves the way toward ambient processing and applications of BP.Few-layered black phosphorus has unique and appealing electronic properties but is easily oxidized in air. Here, the authors covalently functionalize black phosphorus nanosheets with C60 at their edges, providing improved stability and enhanced photoelectrochemical and photocatalytic activities.