• Energy Research

AbstractSolar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight1,2. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials3–5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance6. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm−2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.

In this paper, we report a novel nanobundle structure formed by the hierarchical self-assembly of TGA-capped CdTe quantum dots. HR-TEM confirms the polycrystalline phase of the bundle structure, and that pristine quantum dots are the building units. The steady state absorption and luminescence properties of the pristine quantum dots can be well inherited by the nanobundles. In transient state observation, carrier quenching induced by Auger recombination is found to be remarkably suppressed. Electron delocalizing to close building units is considered to be the reason. Suppression of Auger recombination may earn much more time for charge separation, which makes the novel nanobundle structures suitable for the excellent donor material in solar cell applications.

In recent years, photoelectrochemical (PEC) cells have attracted worldwide attention as cheap alternatives to conventional devices for solar energy conversion. Crucial to the light harvesting and conversion effi ciency of a PEC cell is a nanostructured photoanode, in which the incident photons are captured, electron–hole pairs are generated, and the subsequent electron transfer takes place. [ 1 , 2 ] To realize highly effi cient PEC cells, a nanostructured photoanode should possess several favorable intrinsic characteristics, such as adequate specifi c surface area to permit high photosensitizer loading (in the case of TiO 2 ), direct electron transport pathways for long electron diffusion length, and strong light scattering to promote the light harvesting ability by confi ning the light within the cell. [ 3–6 ] It is thus highly desirable to develop a photoanode that meets all the above requirements. Towards this goal, immense efforts have been concentrated on tailoring the nanometer-scale features of photoanode materials. [ 7 ] Nanoparticle fi lms provide very high surface areas to increase the amount of sensitizer loading, but they lack direct electrical contacts and light-scattering ability. [ 8 , 9 ]

A mixture of CsPbI3 and FAPbI3 is thermodynamically stabilized in the perovskite phase with respect to the pure δ phases.

Ionic liquids can retard the perovskite crystallization with the aim to form compact films with larger and more uniformly distributed grain size. The ionic liquid driven crystallization is exploited to prepared a record planar perovskite solar cell with stabilized power output of 19.5%.

The solar-driven electrochemical reduction of CO2 to fuels and chemicals provides a promising way for closing the anthropogenic carbon cycle. However, the lack of selective and Earth-abundant catalysts able to achieve the desired transformation reactions in an aqueous matrix presents a substantial impediment as of today. Here we introduce atomic layer deposition of SnO2 on CuO nanowires as a means for changing the wide product distribution of CuO-derived CO2 reduction electrocatalysts to yield predominantly CO. The activity of this catalyst towards oxygen evolution enables us to use it both as the cathode and anode for complete CO2 electrolysis. In the resulting device, the electrodes are separated by a bipolar membrane, allowing each half-reaction to run in its optimal electrolyte environment. Using a GaInP/GaInAs/Ge photovoltaic we achieve the solar-driven splitting of CO2 into CO and oxygen with a bifunctional, sustainable and all Earth-abundant system at an efficiency of 13.4%. Electrochemical reduction of CO2 to CO is a route to synthesize fuels, but cheaper and more selective catalysts are required. Using a cell equipped with a bipolar membrane and the same Earth-abundant electrocatalyst at each electrode, Schreier et al. selectively produce CO, powered by a triple-junction photovoltaic.

Highly ordered TiO2@α-Fe2O3 core/shell arrays on carbon textiles (TFAs) have been fabricated by a stepwise, seed-assisted, hydrothermal approach and further investigated as the anode materials for Li-ion batteries (LIBs). This composite TFA anode exhibits superior high-rate capability and outstanding cycling performance. The specific capacity of the TFAs is much higher than that of pristine carbon textiles (CTs) and TiO2 nanorod arrays on carbon textiles (TRAs), indicating a positive synergistic effect of the material and structural hybridization on the enhancement of the electrochemical properties. This composite nanostructure not only provides large interfacial area for lithium insertion/extraction but should also be beneficial in reducing the diffusion pathways for electronic and ionic transport, leading to the improved capacity retention on cycling even at high discharge–charge rates. It is worth emphasizing that the CT substrates also present many potential virtues for LIBs as flexible electronic devices owing to the stretchable, lightweight and biodegradable properties. The fabrication strategy presented here is facile, cost-effective, and scalable, which opens new avenues for the design of optimal composite electrode materials for high performance LIBs.