We present an electrode‐resolved analysis of the performance of platinum‐based abiotically catalyzed glucose fuel cells in realistically simulated tissue fluid (STF) and cerebrospinal fluid (SCF). The presence of amino acids and small organic molecules at physiological concentration leads to a drastic breakdown in fuel cell voltage, resulting in a maximum lifetime of 19 h in STF or 37 h in SCF. The performance loss mainly originates from catalyst poisoning at the anode, which causes 92 % or 80 % of the overall fuel cell voltage loss in STF or SCF, respectively. The results underline the necessity to further investigate and improve catalyst poisoning at the anode under realistic body conditions in order to improve the lifetime of platinum‐based implantable glucose fuel cells.

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We demonstrate an electrodeposition process for the fabrication of highly porous PtCu alloy anodes. In the fabrication process, Pt and different amounts of a second noble metal (Pd, Ru, Au) are repeatedly co‐deposited with Cu from an aqueous electrolyte, followed by selective dealloying of Cu. In this way, highly porous PtCu alloys with roughness factors ranging from 400 to 4000 can be obtained. In all cases, both noble‐metal partners are present on the electrode surface, whereas the majority of copper is likely buried underneath. In addition, we can show that H desorption and CO stripping yield substantially different roughness factors, even when applied to PtCu anodes. Hence, when using or comparing results from different stripping methods, a calibration is required. Compared to PtCu anodes, small additions of Ru (ca. 3 at% Ru) lead to significantly enhanced catalytic activity for the electro‐oxidation of formic acid and methanol, whereas Au‐rich PtCu−Au alloys (ca. 75 at% Au) exhibit significantly improved electrocatalytic activity for glucose oxidation. In some cases, large variations impede the identification of significant differences in electrocatalytic activity. To reduce process variability and to increase the specific surface area, further optimization of the fabrication process is required. Similarly, the deposition of defined alloy compositions will require further investigation, as the composition of electrolyte and deposited alloy do not directly correspond.

The first comprehensive study of the poisoning behavior of physiological amino acids and important tissue fluid constituents on porous platinum electrodes was performed. On the basis of chronoamperometry under physiological conditions, the results are highly relevant for the development of enzyme‐free implantable glucose fuel cells and possibly also glucose sensors. The strongest poisoning was exhibited by positively charged alkaline amino acids and by some of the neutral amino acids, as well as by uric acid and creatinine. In contrast to previous work, sulfur‐containing amino acids showed no poisoning effect. This was explained by the use of highly porous platinum electrodes in the current study and experimental methods that were more relevant for practical applications. Furthermore, comprehensive analysis regarding the degree of recovery in the absence of poisoning species and the extent of electrode regeneration by cyclic voltammetry was performed for each of the amino acids and physiological substances.