Tuning the bandgap of multiferroic solar cells made from Bi2FeCrO6 is achieved by cationic ordering and is shown to dramatically improve their performance.

Bandgap tuning of multiferroic oxide solar cells

Efficient capture of solar energy will be critical to meeting the energy needs of the future. Semiconductor photocatalysis is expected to make an important contribution in this regard, delivering both energy carriers (especially H2 ) and valuable chemical feedstocks under direct sunlight. Over the past few years, carbon dots (CDs) have emerged as a promising new class of metal-free photocatalyst, displaying semiconductor-like photoelectric properties and showing excellent performance in a wide variety of photoelectrochemical and photocatalytic applications owing to their ease of synthesis, unique structure, adjustable composition, ease of surface functionalization, outstanding electron-transfer efficiency and tunable light-harvesting range (from deep UV to the near-infrared). Here, recent advances in the rational design of CDs-based photocatalysts are highlighted and their applications in photocatalytic environmental remediation, water splitting into hydrogen, CO2 reduction, and organic synthesis are discussed.

Smart Utilization of Carbon Dots in Semiconductor Photocatalysis.

The emergence of carbon dots (CDs) has opened up an exciting new field in the science and technology of carbon nanomaterials and has attracted increasing interest in recent years. Due to their diverse physicochemical properties and favourable attributes, such as quantum confinement effects and abundant surface defects, CDs and their derived hybrids have shown exciting and indispensable prospects in the energy conversion and storage fields. Considering the latest developments, in this review, we comprehensively summarize the classification and structure of CDs. Three strategies for structural engineering of CDs are presented and analyzed, in terms of the tuning of size and crystallinity, and the methodologies for surface modification and heteroatom doping, with a focus on the relationship among the synthesis methods, structure and properties of the concerned CDs. More importantly, the recent advances in energy-oriented applications of CDs, including photo- and electro-catalysis, light-emitting diodes, photovoltaic cells, lithium/sodium ion batteries and supercapacitors, will be systematically highlighted. Finally, we discuss and outline the remaining major challenges and opportunities for CDs in the future.

Design and fabrication of carbon dots for energy conversion and storage

Considering metal oxide nanoparticles as important technological materials, authors provide a comprehensive review of researches on metal oxide nanoparticles, their synthetic strategies, and techniques, nanoscale physicochemical properties, defining specific industrial applications in the various fields of applied nanotechnology. This work expansively reviews the recent developments of semiconducting metal oxide gas sensors for environmental gases including CO2, O2, O3, and NH3; highly toxic gases including CO, H2S, and NO2; combustible gases such as CH4, H2, and liquefied petroleum gas; and volatile organic compounds gases. The gas sensing properties of different metal oxides nanoparticles towards specific target gases have been individually discussed. Promising metal oxide nanoparticles for sensitive and selective detection of each gas have been identified. This review also categorizes metal oxides sensors by analyte gas and also summarizes the major techniques and synthesis strategies used in nanotechnology. Additionally, strategies, sensing mechanisms and related applications of semiconducting metal oxide materials are also discussed in detail. Related applications are innumerable trace to ultratrace-level gas sensors, batteries, magnetic storage media, various types of solar cells, metal oxide nanoparticles applications in catalysis, energy conversion, and antennas (including microstrip and patch-type optically transparent antennas), rectifiers, optoelectronic, and electronics.

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Metal oxide nanoparticles and their applications in nanotechnology

Searching for novel functional materials represents an important direction in the research and development of renewable energy. Due to their unique structural and compositional flexibility and high material stability, oxide perovskites and their derivatives have recently been extensively explored as a class of versatile materials for applications in electrocatalysis (EC), photocatalysis (PC) and photovoltaics (PV), showing great promise in terms of catalytic activity and device stability. In this review, we firstly discuss the extreme flexibilities of oxide perovskites in terms of their structures and compositions, which lead to a treasure trove of materials for diverse applications. Secondly, the current status of their applications and challenges in EC, PC and PV are reviewed. We attempt to build the connections between the structural and compositional flexibility and the tunable material properties desirable for various applications.

Oxide perovskites, double perovskites and derivatives for electrocatalysis, photocatalysis, and photovoltaics

A novel nanostructured ferroelectric photovoltaic material, consisting of the ferroelectric lead zirconate titanate (PZT) film and Ag(2) O semiconductor nanoparticles of comparatively narrow bandgap, has demonstrated a remarkable enhancement in the photovoltaic effects and the highest light-electricity conversion efficiency among those PZT-based photodiodes previously reported. This work sheds light on the design and enhanced performance of new optoelectronic and solar energy devices.

Enhancement of Photocurrent in Ferroelectric Films Via the Incorporation of Narrow Bandgap Nanoparticles

Pb(Zr,Ti)O3 (PZT) film with a band gap of 3.6 eV was prepared on In2O3:Sn (ITO) coated glass, and then an amorphous silicon (a-Si) film with a narrow band gap of 1.8 eV was deposited on the PZT/ITO/glass. The short-circuit current of Ag/a-Si/PZT/ITO/glass sample is 2.56 mA cm−2, about 50 times greater than that of Pt/PZT/ITO/glass sample. The energy level of the a-Si film is well matched with that of PZT film, which is beneficial to the transport of UV-visible light-induced charges in the Ag/a-Si/PZT/ITO/glass sample. The photovoltaic output can be tuned by changing the dopant type of the a-Si film, and the maximum photoelectric conversion efficiency is measured to be up to 1.25% in the PZT film with an n-type a-Si film (phosphorus doped).

Above 1% efficiency of a ferroelectric solar cell based on the Pb(Zr,Ti)O3 film

N-Doped nanodots/np+-Si photocathodes for efficient photoelectrochemical hydrogen generation

In the traditional methods such as atomic layer deposition and sputtering, a thin metal oxide layer was usually deposited before the loading of catalysts to protect Si photoelectrodes from oxidation during solar water splitting, and this often results in the transfer of photogenerated carriers from Si to electrolyte more or less inhibited. We here use an atmospheric plasma oxidation method to improve this. A SiO2 protective layer, also an effective passivation layer of Si to increase the life time of carriers, is fabricated on Pt loaded multicrystalline pn+-Si photocathodes. Compared with the un-protected one, the energy conversion efficiency of the plasma-treated Pt/pn+-Si photocathode increases from 6.2% to 8.9% under 100 mW/cm2 Xe lamp, and its stability improves from less than 1–22 h under continuous H2 production. This research provides a conceptual strategy to ensure the direct contact among the Si/Pt/electrolyte and protect and passivate the other part of Si simultaneously.

Surface passivation and protection of Pt loaded multicrystalline pn+ silicon photocathodes by atmospheric plasma oxidation for improved solar water splitting

The invention provides a silicon photocathode and a preparing method thereof. The preparing method comprises the steps that firstly, hydrogen evolution catalyst modification is conducted on the surface, opposite to a photo-anode, of a silicon electrode, and a modified silicon electrode is obtained; and secondly, a passivation protection layer is prepared on the surface, not provided with a hydrogen evolution catalyst layer, of the modified silicon electrode obtained in the first step, and the silicon photocathode is obtained. Compared with the prior art, a hydrogen evolution catalyst makes direct contact with the silicon surface, good ohmic contact can be formed, the series resistance of the electrode can be reduced, the silicon photocathode can have good electrochemical performance, and the fill factor and the water photolysis efficiency of the photocathode are improved.

Yu Xin

Papers

Enhancement of Photocurrent in Ferroelectric Films Via the Incorporation of Narrow Bandgap Nanoparticles

Above 1% efficiency of a ferroelectric solar cell based on the Pb(Zr,Ti)O3 film

N-Doped nanodots/np+-Si photocathodes for efficient photoelectrochemical hydrogen generation

Surface passivation and protection of Pt loaded multicrystalline pn+ silicon photocathodes by atmospheric plasma oxidation for improved solar water splitting

Silicon photocathode and preparing method thereof