Developing earth abundant catalysts for clean energy technologies is vital to address the issues related to the use of fossil fuels and associated pollution, which adversely affects human health. Herein, we report an electrochemically deposited mixed Cu−Co−P film, as a bifunctional catalyst with high stability and activity for the hydrogen evolution reaction (HER, in 0.5 M H 2 SO 4 and 1 M KOH) and the oxygen evolution reaction (OER, in 1 M KOH). In alkaline medium, the Cu−Co− P catalyst outperforms the state-of-art catalysts for both HER (Pt) and OER (RuO 2 ) and is stable under continuous electrolysis for up to 72 hours. Using Cu−Co−P electrodes as both the anode and the cathode increases the activity by ∼2.5 times greater than the integrated performance of RuO 2 (anode) and Pt (cathode) at 1.9 V. The competent bifunctionality of Cu−Co−P is facilitated by Cu incorporation, leading to a low surface passivation of the electrode. This study offers a new strategy to develop earth abundant bimetallic phosphides, which are potential catalysts for many alternative energy technologies.

This work describes the electrocatalysis of amorphous nickel phosphide (Ni‐P) electrodeposited onto copper metal foil, for its use as a non‐noble metal catalyst for the hydrogen evolution reaction (HER) in 0.5 M H2SO4. Although electrodeposition offers many advantages over conventional high temperature and high pressure fabrication techniques, there are very few reports on the preparation of Ni‐P electrocatalysts via electrodeposition. This Ni‐P electrocatalyst exhibits good activity in acidic medium, with a potential of –222 mV to achieve 10 mA cm–2 cathodic current density. This potential is comparable to that of electrodeposited Pt black (–104 mV), and much better than that of electrodeposited Ni (–480 mV). An unusual long‐term stability in acidic medium was demonstrated by the –222 mV potential remaining constant after 5000 cyclic voltammetric sweeps in 0.5 M H2SO4. Importantly, the stoichiometry of the nickel phosphide films can be easily varied from an atomic % of phosphorus from 15 % to as high as 24 % by modifications to the electrodeposition conditions. Such a high phosphorous loading is greater than is generally reported with electrodeposited Ni‐P materials. In addition, we observed Ni‐P films electrodeposited at lower temperatures (∼ 3 °C) result in higher phosphorous loading, which gives rise to enhanced stability as well as activity. Electrodeposited amorphous Ni‐P can therefore be used as an active, stable and Earth‐abundant metal catalyst for the HER in acidic electrolytes.

The question of whether the classical Sand equation reliably predicts the onset of morphological evolution in lithium electrodeposition is addressed and answered in the negative. It is shown that morphology evolution in lithium electrodeposition from organic liquid electrolytes commences at time-scales that are at least 1-2 orders of magnitude lower than Sand’s time. To explain this discrepancy, we present a modified Sand’s approach in which transient multi-phase diffusion through the liquid electrolyte as well as through the solid-electrolyte-interphase layer is considered. Applicability of this approach to lithium electrodeposition is discussed.

Electrochemical atomic layer deposition (e-ALD) technique offers a simple and effective "wet chemistry" approach enabling highprecision monolayer-by-monolayer deposition of metal films. The process of e-ALD of Au involves lead underpotential deposition (Pb UPD ) followed by its redox replacement by a Au monolayer. The time evolution of the deposit mass during "one-pot" Au e-ALD is known to exhibit a unique three-stage response that is presently not well understood. In this work, we probe this response using voltammetry, electrochemical quartz crystal microgravimetry (e-QCM), and chronoamperometry to unravel the underlying mechanistic events during Au e-ALD. The presence of adsorbed Au +3 -ligand complex(es) (Au-L) on the Au surface is established. In stage I of e-ALD, this Au-L adsorbed layer is reduced to Au while a Pb UPD adlayer is formed. In stage II, the Pb UPD adlayer undergoes spontaneous surface-limited redox replacement by nobler Au under open-circuit conditions. Finally, in stage III, readsorption of the Au-L occurs on the newly deposited Au. Quantitative analysis of the deposit mass transients obtained under a variety of conditions provides an estimate of the Au-L mass and its molecular weight.