We present an electrochemical microsensor system for the monitoring of hydrogen peroxide, dissolved hydrogen and dissolved oxygen inside a direct synthesis microreactor. The setup allows the online, in situ measurement of high reactant concentrations by amperometric detection of all three reactants in aqueous solution using chronoamperometric protocols. Hydrogen peroxide is a key chemical for industrial oxidation applications, and its catalyzed direct synthesis is an attractive process route. For the first time, we integrated an electrochemical cell into a high pressure stainless steel microreactor environment (pressures up to 100 bar, pH of 3–4 and presence of bromide) by fabricating sensor plugs with 300 μm platinum microelectrodes encapsulated into a robust epoxy housing. The first microfabricated silver/silver bromide pseudo-reference electrode, integrated by electrodeposition, allowed to obtain a stable measurement potential directly from the electrolyte containing bromide. The investigation of platinum electrochemistry in the presence of bromide by cyclic voltammetry led to the development of chronoamperometric protocols for the stable, precise and reproducible measurement in this environment. Hydrogen peroxide was detected under reaction conditions showing linear behaviour up to 20 mM with high sensitivity of 55 μA cm⁻² mM⁻¹ and excellent stability by application of a diffusion limiting hydrogel layer to the electrode surface. This linear range surpasses most micro- and nanostructured platinum approaches. Oxygen and hydrogen were both measured at elevated pressures up to 70 bar and high dissolved concentrations up to 52 mM and 40 mM with measured sensitivities of 26 μA cm⁻² mM⁻¹ and 356 μA cm⁻² mM⁻¹, respectively. We have successfully shown the application of electrochemical sensors for online, in situ monitoring of analyte concentrations under conditions found in direct synthesis microreactors.

我们提出了一种电化学微传感器系统，用于监测直接合成微反应器内的过氧化氢，溶解氢和溶解氧。该设置允许通过使用计时电流规程对水溶液中的所有三种反应物进行安培检测，在线，就地测量高反应物浓度。过氧化氢是工业氧化应用中的关键化学品，其催化直接合成是一种有吸引力的工艺路线。第一次，我们通过将300μm铂微电极封装在坚固的环氧树脂外壳中的传感器插头制造，将电化学电池集成到高压不锈钢微反应器环境（压力高达100 bar，pH 3-4和存在溴化物）中。通过电沉积而集成的第一个微细加工的银/溴化银伪参比电极可直接从含溴化物的电解质中获得稳定的测量电势。通过循环伏安法在溴化物存在下对铂电化学的研究，促成了计时安培规程的发展，该规程可在这种环境下进行稳定，精确和可重现的测量。在反应条件下检测到过氧化氢，显示线性行为高达20 mM，高灵敏度为55μAcm 通过循环伏安法在溴化物存在下对铂电化学的研究，促成了计时安培规程的发展，该规程可在这种环境下进行稳定，精确和可重现的测量。在反应条件下检测到过氧化氢，显示线性行为高达20 mM，高灵敏度为55μAcm 通过循环伏安法在溴化物存在下对铂电化学的研究，促成了计时安培规程的发展，该规程可在这种环境下进行稳定，精确和可重现的测量。在反应条件下检测到过氧化氢，显示线性行为高达20 mM，高灵敏度为55μAcm^-2  mM ^-1和通过将扩散限制水凝胶层施加到电极表面而获得的优异稳定性。该线性范围超过了大多数微结构和纳米结构的铂方法。氧气和氢气均在高达70 bar的高压下和高达52 mM和40 mM的高溶解浓度下进行测量，分别测得的灵敏度为26μAcm ^-2  mM ^-1和356μAcm ^-2  mM ^-1。我们已经成功地展示了电化学传感器在直接合成微反应器中发现的条件下在线，原位监测分析物浓度的应用。