Electrochemical behaviour of ammonia (NH4+/NH3) on electrochemically grown anodic iridium oxide film (AIROF) electrode

The electrochemical behaviour of ammonia (NH4+/NH3) in sodium perchlorate at pH 9 has been investigated on electrochemically grown anodic iridium oxide film (AIROF) electrode. In base electrolyte at pH 9, the Ir(IV)/Ir(III) surface redox couple exhibits unusually large separation of the oxidation/reduction peaks (Delta E-p similar to 750 mV) due to the local pH changes within the oxide film. These local pH changes are induced by protons released/consumed during the Ir(IV)Ir(III) redox activity. As a consequence, the local pH within AIROF changed up to 10 units during potential cycling. The presence of ammonia at pH 9 prevents these local pH changes because NH4+/NH3 buffer the solution inside the electrode. As a consequence, Delta E-p of Ir(IV)/Ir(III) was reduced 100 mV. It has been shown further that ammonia oxidation is mediated by Ir(V), resulting in the appearance of anodic peaks in forward and back-ward scans. (C) 2009 Elsevier B.V. All rights reserved

Towards circular phosphorus:The need of inter- and transdisciplinary research to close the broken cycle

Phosphorus (P) is an essential element to all living beings but also a finite resource. P-related problems center around broken P cycles from local to global scales. This paper presents outcomes from the 9th International Phosphorus Workshop (IPW9) held 2019 on how to move towards a sustainable P management. It is based on two sequential discussion rounds with all participants. Important progress was reported regarding the awareness of P as finite mineable resource, technologies to recycle P, and legislation towards a circular P economy. Yet, critical deficits were identified such as how to handle legacy P, how climate change may affect ecosystem P cycling, or working business models to up-scale existing recycling models. Workshop participants argued for more transdisciplinary networks to narrow a perceived science-practice/policy gap. While this gap may be smaller in reality as illustrated with a Swiss example, we formulate recommendations how to bridge this gap more effectively. © 2021, The Author(s)