Abstract The use of abundant earth materials for novel electrodes for solar driven electrolysis will play a significant role in the future production of hydrogen as a green energy source. The choice of electrolyte will play a major role in how efficient and stable future photoelectrochemical cells (PEC) operate. A new approach to determining PEC efficiency using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) is investigated to analyze the real-time production of hydrogen and oxygen at platinum electrodes in different electrolyte solutions. The parameters investigated include concentration of electrolyte, surface area of the electrode and the potential applied to the cell. Here, we show the suitability of neutral buffer as an electrolyte on a par with either acid or basic electrolytes. This finding allows for the potential design of solar to hydrogen electrolysers which can operate under mild, neutral and stable conditions using earth abundant materials for hydrogen production. It is also shown how BARDS can readily visualize and track gas evolution in real-time and in-situ in an open system without the need for gas collection. We anticipate that the technique can be utilized in the future evaluation of newly developed electrode materials in terms of efficiency, stability and life span. Acknowledgements This project has received funding from the European Union under grant agreement No 101084261 (FreeHydroCells). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. We also acknowledge support from the Irish Research Council under an Advanced Laureate Award (IRCLA/19/118). This work is partly supported by an Enterprise Ireland Commercialisation Fund as part of the European Regional Development Fund under contract no. CF-2018-0839-P. Keywords: Electrochemistry, spectroscopy, water splitting

The FreeHydroCells project, a European multi-partner consortium led by University College Cork (UCC), has secured nearly €3.75 million in Horizon Europe research funding for over three years of pioneering research. If successful, this initiative could deliver a low-cost solar-to-chemical energy conversion system, utilising sustainable materials. Learn more at freehydrocells.eu. This project is funded by the European Union under grant agreement No. 101084261 (FreeHydroCells) and supported in part by Science Foundation Ireland (SFI) under Grant Number 12/RC/2278-P2 (AMBER).