Yongchao Huang

Oxygen vacancy induced bismuth oxyiodide with remarkably increased visible-light absorption and superior photocatalytic performance.

With the increasingly serious environmental problems, photocatalysis has recently attracted a great deal of attention, with particular focus on water and air purification and disinfection. Herein, we show an electroreduction strategy to improve significantly the solar absorption and donor density of BiOI nanosheet photocatalyst by introducing oxygen vacancies. These oxygen-deficient BiOI nanosheets exhibit an unexpected red shift of about 100 nm in light absorption band and 1 order of magnitude improvement in donor density compared to the untreated BiOI nanosheets and show 10 times higher photocatalytic activity than the untreated BiOI nanosheets for methyl orange (MO) degradation under visible light irradiation. Moreover, the as-prepared oxygen-deficient BiOI nanosheets also have excellent cycling stability and superior photocatalytic performance toward other dye pollutants.

A monolithic metal-free electrocatalyst for oxygen evolution reaction and overall water splitting

Herein, a three-dimensional monolithic and metal-free N-doped porous carbon cloth electrocatalyst was fabricated. Owing to the increased surface area and N-doping, the self-supporting electrocatalyst could effectively catalyze the oxygen evolution reaction, and was also utilized as the anode for an alkaline electrolyzer for the first time with a considerably low overpotential.

Vanadium Nitride Nanowire Supported SnS2 Nanosheets with High Reversible Capacity as Anode Material for Lithium Ion Batteries

The vulnerable restacking problem of tin disulfide (SnS2) usually leads to poor initial reversible capacity and poor cyclic stability, which hinders its practical application as lithium ion battery anode (LIB). In this work, we demonstrated an effective strategy to improve the first reversible capacity and lithium storage properties of SnS2 by growing SnS2 nanosheets on porous flexible vanadium nitride (VN) substrates. When evaluating lithium-storage properties, the three-dimensional (3D) porous VN coated SnS2 nanosheets (denoted as CC-VN@SnS2) yield a high reversible capacity of 75% with high specific capacity of about 819 mAh g(-1) at a current density of 0.65 A g(-1). Remarkable cyclic stability capacity of 791 mAh g(-1) after 100 cycles with excellent capacity retention of 97% was also achieved. Furthermore, discharge capacity as high as 349 mAh g(-1) is still retained after 70 cycles even at a elevated current density of 13 A g(-1). The excellent performance was due to the conductive flexible VN substrate support, which provides short Li-ion and electron pathways, accommodates large volume variation, contributes to the capacity, and provides mechanical stability, which allows the electrode to maintain its structural stability.

Carbon Quantum Dot Surface-Engineered VO2 Interwoven Nanowires: A Flexible Cathode Material for Lithium and Sodium Ion Batteries

The use of electrode materials in their powdery form requires binders and conductive additives for the fabrication of the cells, which leads to unsatisfactory energy storage performance. Recently, a new strategy to design flexible, binder-, and additive-free three-dimensional electrodes with nanoscale surface engineering has been exploited in boosting the storage performance of electrode materials. In this paper, we design a new type of free-standing carbon quantum dot coated VO2 interwoven nanowires through a simple fabrication process and demonstrate its potential to be used as cathode material for lithium and sodium ion batteries. The versatile carbon quantum dots that are vastly flexible for surface engineering serve the function of protecting the nanowire surface and play an important role in the diffusion of electrons. Also, the three-dimensional carbon cloth coated with VO2 interwoven nanowires assisted in the diffusion of ions through the inner and the outer surface. With this unique architecture, the carbon quantum dot nanosurface engineered VO2 electrode exhibited capacities of 420 and 328 mAh g(-1) at current density rate of 0.3 C for lithium and sodium storage, respectively. This work serves as a milestone for the potential replacement of lithium ion batteries and next generation postbatteries.

Chemically Lithiated TiO2 Heterostructured Nanosheet Anode with Excellent Rate Capability and Long Cycle-life for High-Performance Lithium Ion Batteries.

A new form of dual-phase heterostructured nanosheet comprised of oxygen-deficient TiO2/Li4Ti5O12 has been successfully synthesized and used as anode material for lithium ion batteries. With the three-dimensional (3D) Ti mesh as both the conducting substrate and the Ti(3+)/Ti(4+) source, blue anatase Ti(3+)/TiO2nanosheets were grown by a hydrothermal reaction. By controlling the chemical lithiation period of TiO2 nanosheets, a phase boundary was created between the TiO2 and the newly formed Li4Ti5O12, which contribute additional capacity benefiting from favorable charge separation between the two phase interfaces. Through further hydrogenation of the 3D TiO2/Li4Ti5O12 heterostructured nanosheets (denoted as H-TiO2/LTO HNS), an extraordinary rate performance with capacity of 174 mAh g(-1) at 200 C and outstanding long-term cycling stability with only an ∼6% decrease of its initial specific capacity after 6000 cycles were delivered. The heterostructured nanosheet morphology provides a short length of lithium diffusion and high electrode/electrolyte contact area, which could also explain the remarkable lithium storage performance. In addition, the full battery assembled based on the H-TiO2/LTO anode achieves high energy and power densities.

Cost-Effective Alkaline Water Electrolysis Based on Nitrogen- and Phosphorus-Doped Self-Supportive Electrocatalysts

Water splitting into hydrogen and oxygen in order to store light or electric energy requires efficient electrocatalysts for practical application. Cost-effectiveness, abundance, and efficiency are the major challenges of the electrocatalysts. Herein, this paper reports the use of low-cost 304-type stainless steel mesh as suitable electrocatalysts for splitting of water. The commercial and self-support stainless steel mesh is subjected to exfoliation and heteroatom doping processes. The modified stainless steel electrocatalyst displays higher oxygen evolution reaction property than the commercial IrO2 , and comparable hydrogen evolution reaction property with that of Pt. More importantly, an all-stainless-steel-based alkaline electrolyzer (denoted as NESSP//NESS) is designed for the first time, which possesses outstanding stability along with lower overall voltage than the conventional Pt//IrO2 electrolyzer at increasing current densities. The remarkable electrocatalytic properties of the stainless steel electrode can be attributed to the unique exfoliated-surface morphology, heteroatom doping, and synergistic effect from the uniform distribution of the interconnected elemental compositions. This work creates prospects to the utilization of low-cost, highly active, and ultradurable electrocatalysts for electrochemical energy conversion.

Defect Engineering of Bismuth Oxyiodide by IO3- Doping for Increasing Charge Transport in Photocatalysis.

Defect engineering is regarded as one of the most active projects to monitor the chemical and physical properties of materials, which is expected to increase the photocatalytic activities of the materials. Herein, oxygen vacancies and IO3- doping are introduced into BiOI nanosheets via adding NaH2PO2, which can impact the charge carrier dynamics of BiOI photocatalysts, such as its excitation, separation, trap, and transfer. These oxygen-deficient BiOI nanosheets display attractive photocatalytic activities of gaseous formaldehyde degradation and methyl orange under visible light irradiation, which are 5 and 3.5 times higher than the BiOI samples, respectively. Moreover, the comodified BiOI also displayed superior cycling stability and can be used for practical application. This work not only develops an effective strategy for fabricating oxygen vacancies but also offers deep insight into the impact of surface defects in enhancing photocatalysis.

Alkali-modified non-precious metal 3D-NiCo2O4 nanosheets for efficient formaldehyde oxidation at low temperature

Cost-effective catalysts for volatile organic compound (VOC) oxidation are critical to energy conversion and environmental protection. Herein, we developed new, low-cost and high-performance alkali-promoted 3D-NiCo2O4 nanosheet catalysts for HCHO oxidation at room temperature. Benefiting from the large surface area, high adsorption capacity and surface hydroxyls, the alkali-promoted 3D-NiCo2O4 nanosheet catalysts show substantially high catalytic activities for HCHO oxidation. The alkali-promoted 3D-NiCo2O4 nanosheets yield a remarkable HCHO conversion efficiency of 95.3% at room temperature, which is not achieved by any non-precious metal based catalysts at such low temperature. Additionally, the as-prepared alkali-promoted 3D-NiCo2O4 nanosheets retained excellent catalytic performance after 200 h, which can be applied to practical applications. This work provides a feasible approach to improve the efficiency of metal oxides for HCHO oxidation at low temperature.

Three-dimensional TiO2/CeO2 nanowire composite for efficient formaldehyde oxidation at low temperature

We developed a low-cost and high-performance TiO2/CeO2 nanowire-based catalyst for efficient catalytic volatile organic compound oxidation at low temperature. The TiO2/CeO2 nanowires yield a remarkable HCHO conversion efficiency of 60.2% at a low temperature of 60 °C and have excellent catalytic stability as well as good activity for toluene oxidation.

A highly durable catalyst based on CoxMn3–xO4 nanosheets for low-temperature formaldehyde oxidation

Cost-effective catalysts for the oxidation of volatile organic compounds (VOCs) are critical to energy conversion applications and environmental protection. The main bottleneck of this process is the development of an efficient, stable, and cost-effective catalyst that can oxidize HCHO at low temperature. Here, an advanced material consisting of manganese cobalt oxide nanosheet arrays uniformly covered on a carbon textile is successfully fabricated by a simple anodic electrodeposition method combined with post annealing treatment, and can be directly applied as a high-performance catalytic material for HCHO elimination. Benefiting from the increased surface oxygen species and improved redox properties, the as-prepared manganese cobalt oxide nanosheets showed substantially higher catalytic activity for HCHO oxidation. The catalyst completely converted HCHO to CO2 at temperatures as low as 100 °C, and exhibited excellent catalytic stability. Such impressive results are rarely achieved by non-precious metal-based catalysts at such low temperatures.