Shasha Yi

Cadmium Sulfide and Nickel Synergetic Co-catalysts Supported on Graphitic Carbon Nitride for Visible-Light-Driven Photocatalytic Hydrogen Evolution

Design and preparation of noble-metal-free photocatalysts is of great importance for photocatalytic water splitting harvesting solar energy. Here, we report the high visible-light-driven hydrogen evolution upon the hybrid photocatalyst system consisting of CdS nanocrystals and Ni@NiO nanoparticles grown on the surface of g-C3N4. The hybrid system shows a high H2-production rate of 1258.7 μmol h−1 g−1 in the presence of triethanolamine as a sacrificial electron donor under visible light irradiation. The synergetic catalytic mechanism has been studied and the results of photovoltaic and photoluminescence properties show that efficient electron transfer could be achieved from g-C3N4 to CdS nanocrystals and subsequently to Ni@NiO hybrid.

Cobalt Phosphide Modified Titanium Oxide Nanophotocatalysts with Significantly Enhanced Photocatalytic Hydrogen Evolution from Water Splitting

Production of hydrogen from photocatalytic water splitting holds promise as an alternative energy source with superiority of cleanliness, environment friendliness, low price, and sustainability. Perfectly constructing the noble-metal-free and stable hybrid structure photocatalyst is quite essential; herein, for the first time the authors aim to use cobalt phosphide as the cocatalyst on titanium oxide to form a novel hybrid structure to enhance the utilization of the photoexcited electrons in redox reactions for improved photocatalytic H2 evolution activity. Thus, the achieved significantly increased photocatalytic H2 -evolution rate on the optimized CoP/TiO2 (8350 µmol h-1 g-1 ) is 11 times higher than that of the pristine TiO2 . Moreover, this work is expected to spur more insight into synthesizing such novel photofunctional systems, achieving high photocatalytic H2 evolution activity and sufficient stability for solar-to-chemical conversion and utilization.

A novel and highly efficient earth-abundant Cu3P with TiO2 “P–N” heterojunction nanophotocatalyst for hydrogen evolution from water

Semiconductor-based photocatalytic hydrogen (H2) evolution from water is of great importance for solar-to-chemical conversion processes to boost and promote the future hydrogen economy. Here, for the first time, we demonstrate that p-Cu3P coupled with n-TiO2 forms a novel hybrid structure which accelerates electron-hole pair separation and transfer for improved photocatalytic H2-evolution activity. The rate of H2 evolution of the optimized Cu3P/TiO2 (7940 μmol h-1 g-1) is 11 times higher than that of bare TiO2, with an apparent quantum efficiency (AQE) of 4.6%. This work may provide more insight into the synthesis of novel phosphide-based hybrid materials with high photocatalytic H2-evolution activity and sufficient stability for solar-to-chemical conversion and utilization.

A novel architecture of dandelion-like Mo2C/TiO2 heterojunction photocatalysts towards high-performance photocatalytic hydrogen production from water splitting

In the development of photocatalytic hydrogen (H2) production, designing and optimizing photocatalyst nanostructures with efficient charge transfer and separation for catalytically active sites are still a great challenge. Herein, a well-controlled synthetic strategy is developed to prepare an Mo2C/TiO2 hetero-nanostructure, in which the TiO2 3D hierarchical configuration is loaded with highly dispersed Mo2C nanoparticles. This heterostructure achieves the excellent photocatalytic activity of 39.4 mmol h−1 g−1 with its rate ∼25 times higher than that of pristine TiO2. Also, our photocatalysts process excellent long-term durability (>20 h). The impressive photocatalytic H2 activity of Mo2C/TiO2 indicates favourable charge carrier dynamics, as determined by the results of photoluminescence (PL), time-resolved photoluminescence (TRPL), surface photovoltage (SPV), and open circuit potential (OCP) decay curves. Moreover, this study provides a guide for researchers to design new functional materials with excellent hydrogen production activity.

Anchoring and Upgrading Ultrafine NiPd on Room‐Temperature‐Synthesized Bifunctional NH2‐N‐rGO toward Low‐Cost and Highly Efficient Catalysts for Selective Formic Acid Dehydrogenation

Hydrogen is widely considered to be a sustainable and clean energy alternative to the use of fossil fuels in the future. Its high hydrogen content, nontoxicity, and liquid state at room temperature make formic acid a promising hydrogen carrier. Designing highly efficient and low-cost heterogeneous catalysts is a major challenge for realizing the practical application of formic acid in the fuel-cell-based hydrogen economy. Herein, a simple but effective and rapid strategy is proposed, which demonstrates the synthesis of NiPd bimetallic ultrafine particles (UPs) supported on NH2 -functionalized and N-doped reduced graphene oxide (NH2 -N-rGO) at room temperature. The introduction of the NH2 N group to rGO is the key reason for the formation of the ultrafine and well-dispersed Ni0.4 Pd0.6 UPs (1.8 nm) with relatively large surface area and more active sites. Surprisingly, the as-prepared low-cost NiPd/NH2 -N-rGO dsiplays excellent hydrophilicity, 100% H2 selectivity, 100% conversion, and remarkable catalytic activity (up to 954.3 mol H2 (mol catalyst)-1 h-1 ) for FA decomposition at room temperature even with no additive, which is much higher than that of the best catalysts so far reported.

Efficient visible-light-driven hydrogen generation from water splitting catalyzed by highly stable CdS@Mo2C–C core–shell nanorods

Sunlight-driven water splitting using light-absorbing semiconductor-based materials is an ongoing strategy to overcome the world-wide environmental pollution and energy crisis. The construction of core–shell-type nanostructures by coupling of the earth-abundant hydrogen generation catalyst Mo2C to the good photoabsorber CdS may be the best combination for photocatalytic hydrogen generation reaction. Thus, in this work, core–shell nanorods consisting of a CdS core and a Mo2C–C shell have been designed and synthesized for the first time. The as-prepared CdS@Mo2C–C nanorods display an excellent hydrogen generation rate of 17.24 mmol h−1 g−1 relative to pure CdS, which may result from the unique one-dimensional nanostructure, the strong interfacial interaction between the core and shell materials, as well as the broadened visible-light absorption range. Whats more, the existence of C layers in the core–shell nanorods can facilitate transfer of the photogenerated holes to the outer shell of Mo2C–C, and thus protect the inner CdS from photocorrosion to finally achieve high photostability of the catalyst.

Amorphizing of Cu Nanoparticles toward Highly Efficient and Robust Electrocatalyst for CO2 Reduction to Liquid Fuels with High Faradaic Efficiencies

Conversion of carbon dioxide (CO2 ) into valuable chemicals, especially liquid fuels, through electrochemical reduction driven by sustainable energy sources, is a promising way to get rid of dependence on fossil fuels, wherein developing of highly efficient catalyst is still of paramount importance. In this study, as a proof-of-concept experiment, first a facile while very effective protocol is proposed to synthesize amorphous Cu NPs. Unexpectedly, superior electrochemical performances, including high catalytic activity and selectivity of CO2 reduction to liquid fuels are achieved, that is, a total Faradaic efficiency of liquid fuels can sum up to the maximum value of 59% at -1.4 V, with formic acid (HCOOH) and ethanol (C2 H6 O) account for 37% and 22%, respectively, as well as a desirable long-term stability even up to 12 h. More importantly, this work opens a new avenue for improved electroreduction of CO2 based on amorphous metal catalysts.

Carbon quantum dot sensitized integrated Fe2O3@g-C3N4 core–shell nanoarray photoanode towards highly efficient water oxidation

The construction of integrated heterojunction system photoelectrodes for solar energy conversion is indubitably an efficient alternative due to their effectiveness in charge separation and optimizing the ability for reduction and oxidation reactions. Here, an integrated photoanode constructed with carbon quantum dot (CQD) sensitized Ti:Fe2O3@GCNN (where GCNNs are graphitic carbon nitride nanosheets) core–shell nanoarrays is demonstrated, showing an excellent photocurrent density as high as 3.38 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (VRHE), 2-fold higher than that of pristine Ti:Fe2O3, which is superior over that of recently reported promising photoanodes. In this ternary system (Ti:Fe2O3@GCNN-CQDs), each component plays a specific role in the process towards superior PEC water oxidation: (i) the vectorial hole transfer of Ti:Fe2O3 → g-C3N4 → CQDs; (ii) the introduction of CQDs leads to high catalytic activity for H2O2 decomposition contributing a high rate activity for water oxidation via a two-step-two-electron water-splitting process; (iii) the favorable electron transport behavior of CQDs. This controlled structure design represents one scalable alternative toward the development of photoanodes for high-efficiency water splitting.

Non-noble-metal bismuth nanoparticle-decorated bismuth vanadate nanoarray photoanode for efficient water splitting

Sunlight-driven photoelectrochemical (PEC) water splitting using earth-abundant semiconductor-based materials offers one promising strategy to produce attainable and sustainable carbon free energy. Herein, we demonstrate for the first time that a heterojunction nanostructure of a Bi/BiVO4 photoanode is fabricated by directly coupling semimetal Bi nanoparticles to BiVO4 nanoarrays, showing excellent water oxidation performance. The as-obtained photoanode exhibits a remarkable photocurrent density of 1.96 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (vs. RHE) under AM 1.5G (100 mW cm−2) irradiation, which is approximately 2-fold higher than that of the pristine BiVO4. Based on the detailed analyses of J–V, i–t, M–S and EIS plots, the reason for the high photocurrent density of Bi/BiVO4 can be attributed to the improved charge separation efficiency, the enhanced hole injection efficiency and the suppressed back reaction of water oxidation.

Non-noble metals applying to solar water splitting

The generation of hydrogen (H2) induced by solar water splitting over semiconductors has been regarded as one of the most promising strategies for providing clean and renewable energy sources for future energy sustainability. The key to achieving high solar-to-chemical-energy conversion efficiency is the design of efficient structures with high charge separation and transportation; thus, the development of inexpensive and functional nanomaterials has become quite necessary. Photocatalysts based on non-noble metals have great potential as substitutes for noble metal-based catalysts for H2 generation from photocatalytic (PC) and/or photoelectrochemical (PEC) water splitting. In this review, we present the recent progress on non-noble metal-based nanostructures using in PC and/or PEC water splitting and reveal their underlying roles in affecting the behavior of charge carriers in specific reactions. This review should bring new insight and inspire further innovative work on designing non-noble metals involved in solar water splitting.