Noble‐metal‐free catalytic nanoparticles hold the promise being abundant, low‐cost materials having a small environmental footprint and excellent performance, albeit inferior to that of noble metal counterparts. Several materials have a long‐standing history of success in photocatalysis, in particular titanium dioxide, and in recent years more complex oxides and added functionality have emerged with enhanced performance. We will discuss different approaches related to the use of non‐centrosymmetric and polar oxide nanoparticles and how the bulk photovoltaic effect, piezoelectricity, and pyroelectricity add to photocatalysis and tribocatalysis. We pay special attention to discriminate between the role of free versus that of bound charges within the catalyst, which is crucial to disentangle the different contributions to the catalytic reaction for the benefit of the overall enhanced catalytic performance in e.g. wastewater treatment and ultimately water‐splitting.

With the rapid proliferation of consumer electronics in our day to day lives, there is an ever increasing demand for flexible electronic devices which are low cost, easy to fabricate and deliver reliable performance. In this work, we report fabrication of symmetric poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/WO 3 /PEDOT:PSS memory cells by inkjet printing on transparent, flexible polyethylene naphthalate (PEN) substrates. The cells show resistive switching behavior with two stable resistance states. The current conduction across the interface between the PEDOT:PSS electrode and dielectric WO 3 is determined by localized filamentary features which is space charge limited in the high resistance state, facilitated through the migration of oxygen vacancies at low voltages (<2 V) whereas Schottky emission dominates the current conduction for higher voltages (>2 V). The cells show good retentivity and endurance (>6000 cycles). The cells are entirely sinter free and no electroforming is required to activate them. These characteristics make them suitable for the next generation of flexible non-volatile memory devices.

Printable and flexible memory devices are attracting a lot of interest in several emerging technological applications for the development of flexible electronics, such as interconnections/wearables/smart devices for IoT. In this work, we report on the fabrication of flexible, transparent, and fully inkjet-printed resistive random access memory cells (ReRAM) using PEDOT: PSS/ZnO/PEDOT: PSS structures. The electrical characteristics were studied, including the determination of SCLC as the dominant charge transport mechanism. In addition, the bending performance and the transparency of the devices was tested in order to confirm the reliable operation and reproducibility of the cells. The switching for the printed structures of PEDOT:PSS/ZnO/PEDOT:PSS was led through the formation and dissolution of a stable oxygen vacancy filament, as confirmed by conductive atomic force microscopy. While the conduction mechanism for the high resistance state (HRS) was attributed to the space charge limited conduction (SCLC) mechanism. The switching of the memory cells, their endurance and retention properties were analyzed and indicated the stability of the HRS and low resistance state (LRS) for more than 104 cycles and 105 s comparable to ZnO-based ReRAM produced by clean-room techniques. The study of the mechanical flexibility of the cells shows that up to 700 bending cycles can be reached without significantly changing the switching characteristics.

Noble-metal-free catalytic nanoparticles hold the promise being abundant, low-cost materials having a small environmental footprint and excellent performance, albeit inferior to that of noble metal counterparts. Several materials have a long-standing history of success in photocatalysis, in particular titanium dioxide, and in recent years more complex oxides and added functionality have emerged with enhanced performance. We will discuss different approaches related to the use of non-centrosymmetric and polar oxide nanoparticles and how the bulk photovoltaic effect, piezoelectricity, and pyroelectricity add to photocatalysis and tribocatalysis. We pay special attention to discriminate between the role of free versus that of bound charges within the catalyst, which is crucial to disentangle the different contributions to the catalytic reaction for the benefit of the overall enhanced catalytic performance in e.g. wastewater treatment and ultimately water-splitting.

Herein, we propose a facile fabrication procedure for platinum (Pt) nanoprobes. Our approach consists in performing a one-step electrochemical etching using a mixture of DI water, acetone, and CaCl2. Our technique is self-terminated and thus does not necessitate a cut-off circuit nor other sophisticated equipment or set-up commonly used in the fabrication process of Pt nanoprobes. The Pt nanoprobes thereby manufactured demonstrate small tip radii, a high aspect-ratio, no detectable surface contamination, and good reproducibility.