Recent Advances in Ultralow-Pt-Loading Electrocatalysts for the Efficient Hydrogen Evolution.

Hydrogen production from water electrolysis provides a green and sustainable route. Platinum (Pt)-based materials have been regarded as efficient electrocatalysts for the hydrogen evolution reaction (HER). However, the large-scale commercialization of Pt-based catalysts suffers from the high cost. Therefore, ultralow-Pt-loading electrocatalysts, which can reach the balance of low cost and high HER performance, have attracted much attention. In this review, representative promising synthetic strategies, including wet chemistry, annealing, electrochemistry, photochemistry, and atomic layer deposition are summarized. Further, the interaction between different electrocatalyst components (transition metals and their derivatives) and Pt is discussed. Notably, this interaction can effectively accelerate the kinetics of the HER, enhancing the catalytic activity. At last, current challenges and future perspectives are briefly discussed

CuInS2/ZnS nanocrystals as sensitisers for NiO photocathodes

Nickel oxide (NiO) is the most universally studied photocathode to date, however, its poor fill factor (FF) makes its efficiency much lower than its counterpart, n-type photoanodes. Its significance in photovoltaics is based on the potential to fabricate tandem photoelectrodes in order to enhance the overall efficiency of the existing devices. Furthermore, limited work on the sensitisation of NiO with semiconducting nanocrystals (NCs) exists. For the first time, we have fabricated NiO photocathodes sensitised with aqueous CuInS2/ZnS NCs. The NCs were chemically bound to the NiO films with the aid of carboxyl and thiol groups. This was achieved without modifying the bulk surface properties of NiO. Binding of the NCs was investigated using TEM, SEM, XPS, XANES, EXAFS modelling and ToF-SIMS. NiO films were assembled into CuInS2/ZnS NC sensitised photocathodes and their photovoltaic properties were compared to those of unsensitised and dye-sensitised NiO solar cells. We demonstrate that nontoxic NCs can be used to sensitise NiO photocathodes to achieve an (almost) all-inorganic system

Photo-doping of plasma-deposited polyaniline (PAni)

Although polyaniline (PAni) has been studied extensively in the past, little work has been done on producing films of this material via plasma deposition. We have synthesized and analysed the photoresponse behavior of plasma-deposited polyaniline films and proceeded to dope the films using light and with various metal ions. Upon illumination, the photocurrent responses of the thin plasma films increased over time, and the response was dependent on the film thickness. On doping the film with metal ions, the photocurrent densities were enhanced from nano- to micro-amperes per square centimeters. Doping seemed, however, to cause the films to become unstable. Despite this setback, which requires further research, the drastic increase in current shows great promise for the development of plasma-deposited polyaniline films for application in the area of organic electronics and photovoltaics

Trends in Aluminium-Based Intercalation Batteries

Over the last decade, optimizing energy storage has become significantly important in the field of energy conversion and sustainability. As a result of immense progress in the field, cost‐effective and high performance batteries are imperative to meeting the future demand of sustainability. Currently, the best performing batteries are lithium‐ion based, but limited lithium (Li) resources make research into alternatives essential. In recent years, the performance of aluminium‐ion batteries has improved remarkably in all battery‐relevant metrics, which renders them a promising alternative. Compared with monovalent Li‐ion batteries, aluminium (Al) cations can carry three positive charges, which could result in higher energy densities. This review describes recent developments in Al‐based cathode materials. The major goal of this review is to highlight strengths and weaknesses of various different approaches and provide guidelines for future research

Lewis Base Passivation Mediates Charge Transfer at Perovskite Heterojunctions

Understanding interfacial charge transfer processes such as trap-mediated recombination and injection into charge transport layers (CTLs) is crucial for the improvement of perovskite solar cells. Herein, we reveal that the chemical binding of charge transport layers to CH3NH3PbI3 defect sites is an integral part of the interfacial charge injection mechanism in both n-i-p and p-i-n architectures. Specifically, we use a mixture of optical and X-ray photoelectron spectroscopy to show that binding interactions occur via Lewis base interactions between electron-donating moieties on hole transport layers and the CH3NH3PbI3 surface. We then correlate the extent of binding with an improvement in the yield and longer lifetime of injected holes with transient absorption spectroscopy. Our results show that passivation-mediated charge transfer has been occurring undetected in some of the most common perovskite configurations and elucidate a key design rule for the chemical structure of next-generation CTLs

Ambient Fabrication of Organic–Inorganic Hybrid Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells (PSCs) have attracted significant attention in recent years due to their high‐power conversion efficiency, simple fabrication, and low material cost. However, due to their high sensitivity to moisture and oxygen, high efficiency PSCs are mainly constructed in an inert environment. This has led to significant concerns associated with the long‐term stability and manufacturing costs, which are some of the major limitations for the commercialization of this cutting‐edge technology. Over the past few years, excellent progress in fabricating PSCs in ambient conditions has been made. These advancements have drawn considerable research interest in the photovoltaic community and shown great promise for the successful commercialization of efficient and stable PSCs. In this review, after providing an overview to the influence of an ambient fabrication environment on perovskite films, recent advances in fabricating efficient and stable PSCs in ambient conditions are discussed. Along with discussing the underlying challenges and limitations, the most appropriate strategies to fabricate efficient PSCs under ambient conditions are summarized along with multiple roadmaps to assist in the future development of this technology

Carbon nanotubes in TiO2 nanofiber photoelectrodes for high-performance perovskite solar cells

1D semiconducting oxides are unique structures that have been widely used for photovoltaic (PV) devices due to their capability to provide a direct pathway for charge transport. In addition, carbon nanotubes (CNTs) have played multifunctional roles in a range of PV cells because of their fascinating properties. Herein, the influence of CNTs on the PV performance of 1D titanium dioxide nanofiber (TiO2 NF) photoelectrode perovskite solar cells (PSCs) is systematically explored. Among the different types of CNTs, single‐walled CNTs (SWCNTs) incorporated in the TiO2 NF photoelectrode PSCs show a significant enhancement (≈40%) in the power conversion efficiency (PCE) as compared to control cells. SWCNTs incorporated in TiO2 NFs provide a fast electron transfer within the photoelectrode, resulting in an increase in the short‐circuit current (J sc) value. On the basis of our theoretical calculations, the improved open‐circuit voltage (V oc) of the cells can be attributed to a shift in energy level of the photoelectrodes after the introduction of SWCNTs. Furthermore, it is found that the incorporation of SWCNTs into TiO2 NFs reduces the hysteresis effect and improves the stability of the PSC devices. In this study, the best performing PSC device constructed with SWCNT structures achieves a PCE of 14.03%

SWCNT photocathodes sensitised with InP/ZnS core-shell nanocrystals

Increasing the light harvesting efficiency of photocathodes is an integral part of optimising the future efficiencies of solar technologies. In contrast to the more extensively studied photoanode systems, current state-of-the-art photocathodes are less efficient and are commonly replaced with rare and expensive materials such as platinum group metals. The significance of photocathodes is in the development of tandem electrodes, enhancing the performance of existing devices. Carbon nanotubes are promising candidates for photocathodes, which, in addition to their p-type conductivity and catalytic properties, possess a suite of unique optical and electrical attributes. This work describes the fabrication of single walled carbon nanotube (SWCNT) photocathodes sensitised with indium phosphide/zinc sulfide (InP/ZnS) core–shell nanocrystals (NCs). Under air mass (AM) 1.5 conditions, the sensitisation of SWCNT photocathodes with InP/ZnS NCs increased the photocurrent density by 350% of the unsensitised output. This significant enhancement of current density demonstrates the potential of InP/ZnS NCs as effective sensitisers to improve the performance of carbon-based photocathode thin films

Copper Metallopolymer Catalyst for the Electrocatalytic Hydrogen Evolution Reaction (HER)

Conjugated polymers with stabilizing coordination units for single-site catalytic centers are excellent candidates to minimize the use of expensive noble metal electrode materials. In this study, conjugated metallopolymer, POS[Cu], was synthesized and fully characterized by means of spectroscopical, electrochemical, and photophysical methods. The copper metallopolymer was found to be highly active for the electrocatalytic hydrogen generation (HER) in an aqueous solution at pH 7.4 and overpotentials at 300 mV vs. reversible hydrogen electrode (RHE). Compared to the platinum electrode, the obtained overpotential is only 100 mV higher. The photoelectrochemical tests revealed that the complexation of the conjugated polymer POS turned its intrinsically electron-accepting (p-type) properties into an electron-donor (n-type) with photocurrent responses ten times higher than the organic photoelectrode

Copper Metallopolymer Catalyst for the Electrocatalytic Hydrogen Evolution Reaction (HER)

Conjugated polymers with stabilizing coordination units for single-site catalytic centers are excellent candidates to minimize the use of expensive noble metal electrode materials. In this study, conjugated metallopolymer, POS[Cu], was synthesized and fully characterized by means of spectroscopical, electrochemical, and photophysical methods. The copper metallopolymer was found to be highly active for the electrocatalytic hydrogen generation (HER) in an aqueous solution at pH 7.4 and overpotentials at 300 mV vs. reversible hydrogen electrode (RHE). Compared to the platinum electrode, the obtained overpotential is only 100 mV higher. The photoelectrochemical tests revealed that the complexation of the conjugated polymer POS turned its intrinsically electron-accepting (p-type) properties into an electron-donor (n-type) with photocurrent responses ten times higher than the organic photoelectrode