Dynamic defects boost in-situ H2O2 piezocatalysis for water cleanup.

Creating efficient catalysts for simultaneous H2O2 generation and pollutant degradation is vital. Piezocatalytic H2O2 synthesis offers a promising alternative to traditional methods but faces challenges like sacrificial reagents, harsh conditions, and low activity. In this study, we introduce a cobalt-loaded ZnO (CZO) piezocatalyst that efficiently generates H2O2 from H2O and O2 under ultrasonic (US) treatment in ambient aqueous conditions. The catalyst demonstrates exceptional performance with ~50.9% TOC removal of phenol and in situ generation of 1.3 mM H2O2, significantly outperforming pure ZnO. Notably, the CZO piezocatalyst maintains its H2O2 generation capability even after multiple cycles, showing continuous improvement (from 1.3 mM to 1.8 mM). This is attributed to the piezoelectric electrons promoting the generation of dynamic defects under US conditions, which in turn promotes the adsorption and activation of oxygen, thereby facilitating efficient H2O2 production, as confirmed by EPR spectrometry, XPS analysis, and DFT calculations. Moreover, the CZO piezocatalysts maintain outstanding performance in pollutant degradation and H2O2 production even after long periods of inactivity, and the deactivated catalyst due to metal ion dissolution could be rejuvenated by pH adjustment, offering a sustainable solution for wastewater purification.

A polymer tethering strategy to achieve high metal loading on catalysts for Fenton reactions.

The development of heterogenous catalysts based on the synthesis of 2D carbon-supported metal nanocatalysts with high metal loading and dispersion is important. However, such practices remain challenging to develop. Here, we report a self-polymerization confinement strategy to fabricate a series of ultrafine metal embedded N-doped carbon nanosheets (M@N-C) with loadings of up to 30 wt%. Systematic investigation confirms that abundant catechol groups for anchoring metal ions and entangled polymer networks with the stable coordinate environment are essential for realizing high-loading M@N-C catalysts. As a demonstration, Fe@N-C exhibits the dual high-efficiency performance in Fenton reaction with both impressive catalytic activity (0.818 min-1) and H2O2 utilization efficiency (84.1%) using sulfamethoxazole as the probe, which has not yet been achieved simultaneously. Theoretical calculations reveal that the abundant Fe nanocrystals increase the electron density of the N-doped carbon frameworks, thereby facilitating the continuous generation of long-lasting surface-bound •OH through lowering the energy barrier for H2O2 activation. This facile and universal strategy paves the way for the fabrication of diverse high-loading heterogeneous catalysts for broad applications.

Selective Production of CO from Organic Pollutants by Coupling Piezocatalysis and Advanced Oxidation Processes.

To date, the chemical conversion of organic pollutants into value-added chemical feedstocks rather than CO2 remains a major challenge. Herein, we successfully developed a coupled piezocatalytic and advanced oxidation processes (AOPs) system for achieving the conversion of various organic pollutants to CO. The CO product stems from the specific process in which organics are first oxidized to carbonate through peroxymonosulfate (PMS)-based AOPs, and then the as-obtained carbonate is converted into CO by piezoelectric reduction under ultrasonic (US) vibration by using a Co3 S4 /MoS2 catalyst. Experiments and DFT calculations show that the introduction of Co3 S4 not only effectively promotes the transfer and utilization of piezoelectric electrons but also realizes highly selective conversion from carbonate to CO. The Co3 S4 /MoS2 /PMS system has achieved selective generation of CO in actual complex wastewater treatment for the first time, indicating its potential practical applicability.

Light-Induced Generation and Regeneration of Oxygen Vacancies in BiSbO4 for Sustainable Visible Light Photocatalysis.

Oxygen vacancy (OV)-containing semiconductor photocatalysts have been extensively studied and applied in environmental and energy fields, but there are a few studies concerning the mechanisms of inactivation and regeneration of OVs to prevent the catalysts from deactivation. In this paper, we put forward a novel in situ method to introduce the OVs into BiSbO4 (BiSbO4-OV) via UV-light-induced breaking down of Bi-O and Sb-O bonds. The formation of OVs could broaden the photoresponse range and improve the charge carrier separation as confirmed by density functional theory calculation and UV and photoluminescence spectroscopy. The unique electronic structure of OVs endowed BiSbO4 with high visible light photocatalytic NO activity. It was significant to reveal that oxygen in the air could fill the OV sites during the photocatalytic reaction and the consumption of the OVs led to the direct deactivation of BiSbO4-OV. By re-irradiation of the deactivated photocatalysts, BiSbO4-OV could get back to its initial state, realizing the refreshment of OVs for sustainable photocatalysis. Additionally, the visible light photocatalytic NO conversion pathway on BiSbO4-OV was uncovered via in situ diffuse reflectance infrared Fourier transform spectroscopy based on the identification of the reaction intermediates and products. The light-induced generation and regeneration of OVs could also be extended to other semiconductors for sustainable visible light photocatalysis.