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Solar-driven semiconductor photocatalysts are highly appealing in applications of environmental remediation and energy conversion. However, photocatalytic reactions, particularly oxygen evolution reaction (OER), are often constrained by the swift recombination of electron–hole pairs, thereby resulting in low reaction efficiency. Although it is effective to separate charge carriers by constructing heterojunctions to form built-in electric field, the lattice mismatch and inefficient interlayer charge transfer of heterojunctions in the photocatalysts limit their further development. Here, we propose a new strategy by constructing an internal electric field for OER through an individual piezoelectric two-dimensional material. The results indicate that the piezoelectric effect regulates the electronic structure, reduces bandgap, improves light absorption efficiency, and that the displacement of positive and negative charge centers is the key factor in the enhanced OER. This research indicates the feasibility of combining piezoelectric properties of two-dimensional materials with OER (1.19 eV), providing new insights and guidance for applying the piezoelectric effect in the OER and opening up a way to promote efficient separation of charge carriers. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) is a kind of wide-bandgap semiconductor. Nano-TiO2 devices exhibit size-dependent and novel photoelectric performance due to their quantum limiting effect, high absorption coefficient, high surface-volume ratio, adjustable band gap, etc. Due to their excellent electronic performance, abundant presence, and high cost performance, they are widely used in various application fields such as memory, sensors, and photodiodes. This article provides an overview of the most recent developments in the application of nanostructured TiO2-based optoelectronic devices. Various complex devices are considered, such as sensors, photodetectors, light-emitting diodes (LEDs), storage applications, and field-effect transistors (FETs). This review of recent discoveries in TiO2-based optoelectronic devices, along with summary reviews and predictions, has important implications for the development of transitional metal oxides in optoelectronic applications for researchers. [ABSTRACT FROM AUTHOR]

The development and exploration of electrocatalysts with the high reactive and abundant availability is still extremely crucial in electrocatalytic overall water splitting. Herein, a novel globular-flowers-like MnO 2 /Co 3 (PO 4) 2 (denoted as MnCoPi) electrocatalyst on nickel foam was successfully prepared through a simple one-step electrodeposition method. The MnCoPi electrocatalyst simultaneously delivers remarkable electrocatalytic activities for hydrogen evolution reaction (HER) with overpotentials (η 10) reaching 102 mV and oxygen evolution reaction (OER) with overpotentials (η 10) up to 225 mV in 1 M KOH solution. Furthermore, the assembled electrolyzer cell utilizing MnCoPi as the cathode and anode only requires a low voltage of 1.55 V to achieve a current density of 10 mA cm−2. Moreover, the developed MnCoPi electrocatalyst shows excellent stability during continuous operation for 48 h in OER, HER and overall water splitting process. Compared with the pristine MnO 2 , the significant electrocatalytic properties of MnCoPi can mainly be attributed to the improved physicochemical properties such as distinctive globular-flowers-like morphology, huge specific surface areas and abundant porosity structure, low electrochemical resistance, especially for the formed heterojunction between MnO 2 and Co 3 (PO 4) 2 , which can provide abundant reactive sites and accelerated electron transfer, etc. Consequently, this work provides a new avenue for the development of efficient and stable bifunctional electrocatalysts for overall water splitting. [Display omitted] • A novel MnCoPi catalyst was synthesized by one-step electrodeposition method. • The catalyst achieves outstanding HER and OER activity with robust stability. • The synergy between MnO 2 and Co 3 (PO 4) 2 improved electron transfer. [ABSTRACT FROM AUTHOR]