Neutral pH Water Research Articles

Effect of water level and water quality on small‐sized and juvenile fish assemblages in the littoral zones of the Zambezi/Chobe floodplain

AbstractThe effect of flooding phase and water quality on the littoral fish species of the Zambezi/Chobe floodplain was assessed between March 2017 and February 2018. Using the similarity percentage analyses (SIMPER), a 61.9% dissimilarity was detected in fish assemblages among the four flooding phases of the Zambezi/Chobe floodplain (rising, peak, recession and low flooding phase). Cichlids (63.1%) were the most dominant taxa during the peak flooding phase while cyprinids were dominant during the rising (40.7%), recession (45.3%) and low flooding phases (40.9%), respectively. Juveniles of the two commercially important species, Oreochromis andersonii and Coptodon rendalli, were among the four abundant species across the four flooding phases of the Zambezi/Chobe floodplain. Higher densities of these two species were in synchrony with the peak flooding phase, characterised by high levels of dissolved oxygen (5.7 ± 1.0 mg/L), neutral pH (7.9) and moderate water temperature (27.6 ± 1.1°C). During the flood recession phase, a severe decline in juvenile of the commercially important species (O. andersonii and C. rendalli) coincided with fish migration off the littoral zone into the main river at a mean size between 70 and 80 mm SL. Generally, the observed variations in the fish species composition during the different stages of flooding might reflect the influence of water quality and water volume to sustain large fish assemblages on the littoral zone of the Zambezi/Chobe floodplain. Any change in the natural flow and reduction in water volume of the Zambezi/Chobe floodplain might negatively affect the recruitment of juvenile fish into adult populations.

Photochemical hydrogen evolution from cobalt microperoxidase-11

A photochemical system utilizing the semisynthetic biomolecular catalyst acetylated cobalt microperoxidase-11 (CoMP11-Ac) along with [Ru(bpy)3]2+ as a photosensitizer and ascorbic acid as an electron donor is shown to generate hydrogen from water in a visible light-driven reaction. The reductive quenching pathway facilitated by photoexcited [Ru(bpy)3]2+ overcomes the high overpotential observed for CoMP11-Ac in electrocatalysis, yielding turnover numbers ranging from 606 to 2390 (2 μM – 0.1 μM CoMP11-Ac). The longevity of CoMP11-Ac in the photochemical system, sustaining catalysis for over 20 h, is in contrast to its previously reported behavior in an electrochemical system where catalysis slows after 15 min. Proton reduction turnover number and rate are highest at a neutral pH, a rare feature among cobalt catalysts in similar photochemical systems, which typically function best under acidic conditions. Incorporating biomolecular components into the design of catalysts for photochemical systems may address the need for hydrogen generation from neutral-pH water sources.

Increasing the rate of the hydrogen evolution reaction in neutral water with protic buffer electrolytes

Electrocatalytic generation of H2 is challenging in neutral pH water, where high catalytic currents for the hydrogen evolution reaction (HER) are particularly sensitive to the proton source and solution characteristics. A tris(hydroxymethyl)aminomethane (TRIS) solution at pH 7 with a [2Fe-2S]-metallopolymer electrocatalyst gave catalytic current densities around two orders of magnitude greater than either a more conventional sodium phosphate solution or a potassium chloride (KCl) electrolyte solution. For a planar polycrystalline Pt disk electrode, a TRIS solution at pH 7 increased the catalytic current densities for H2 generation by 50 mA/cm2 at current densities over 100 mA/cm2 compared to a sodium phosphate solution. As a special feature of this study, TRIS is acting not only as the primary source of protons and the buffer of the pH, but the protonated TRIS ([TRIS-H]+) is also the sole cation of the electrolyte. A species that is simultaneously the proton source, buffer, and sole electrolyte is termed a protic buffer electrolyte (PBE). The structure-activity relationships of the TRIS PBE that increase the HER rate of the metallopolymer and platinum catalysts are discussed. These results suggest that appropriately designed PBEs can improve HER rates of any homogeneous or heterogeneous electrocatalyst system. General guidelines for selecting a PBE to improve the catalytic current density of HER systems are offered.

Hydrogeochemistry in the Yukon-Tanana upland region of east-central Alaska: Possible exploration tool for porphyry-style deposits

A hydrogeochemical study using high resolution ICP-MS was undertaken at the Taurus and other porphyry Cu–Mo(-Au) occurrences and Ag–Au–Cu (+/− Pb, Zn) occurrences with epithermal-style characteristics in the Yukon-Tanana upland region of eastern Alaska. Surface water samples were collected from 30 sites on creeks that drain known deposits and occurrences and surrounding presumably unmineralized areas. Water samples for the entire ~9 km length of McCord Creek, which drains the Taurus deposit, and those from streams draining the areas at and near the Bluff and Dennison porphyry occurrences have high conductivity values (492–1250 μS/cm) and consistently high concentrations of B (3–250 μg/L), Co (2.3–42 μg/L), Mn (339–4750 μg/L), Re (0.012–0.1 μg/L), and SO42− (>200 mg/L), all of which are well above the median value for this data set and significantly greater than concentrations in water samples from the unmineralized areas. These are the best pathfinder elements specifically for porphyry style deposits because most of them are not anomalous in waters near epithermal occurrences. Copper concentrations are high (up to 115 μg/L) in some low-pH water samples from McCord Creek and drainages around Bluff, and a few near neutral pH waters have high molybdenum (>1 μg/L), but neither element is consistently anomalous in close vicinity to the porphyry occurrences, possibly due to a metal-poor, sulfide-poor leached cap (average of ~50 m) that overlies supergene and hypogene mineralized zones and is the dominant rock at surface. High concentrations of Bi and/or As occur in many waters associated with mineralized areas, particularly the Bluff and Dennison occurrences. In general, the element associations related to porphyry deposits reflect the deposit mineralogy, as well as size of the footprint related to alteration and mineralization.

Photocatalytic Hydrogen Generation from pH-Neutral Water by a Flexible Tri-Component Composite

In this work we examine the benefits of using carefully designed tri-component composites to fabricate flexible photocathode electrodes for photo-electrocatalytic hydrogen (H2) generation from neutral pH water. We report H2 production by a tri-component composite thin-film containing CuO nanowires (CuO NW), reduced graphene oxide (rGO) and polypyrrole (PPy). At − 1.1 V vs Ag/AgCl in 0.5 M Na2SO4 (pH 6.8) with a hole-scavenger, under weak light illumination, he photocurrent performance was fivefold greater than the bi-component CuO–rGO control having the same absolute quantities of CuO and rGO. It was 30-fold greater than the CuO–PPy control. The tri-component CuO–rGO–PPy thin film therefore displayed an active H2-generating capacity compare with its bi-component analogues. It, effectively, exploited the advantages of each component, including the suppression of charge recombination afforded by the rGO, and the photocorrosion protection, immobilization and flexibility afforded by the PPy, whilst avoiding their disadvantages. Entry for the Table of contents

Rejection of harsh pH saline solutions using graphene membranes

Water security is a pressing issue for global citizens in the 21st century. Concerns over clean water supply, and the environmental impact of industrial waste water, make water treatment a world-wide problem requiring a simple and effective solution. Membrane distillation is an emerging water purification technique that complements state-of-the-art reverse osmosis processes. Membrane distillation achieves high rejection over a range of salt concentrations while maintaining flux, using a temperature differential as opposed to pressure across the membrane. Importantly the process can be driven using low grade waste heat energy. Current membranes used in membrane distillation do not guarantee stable membrane performance under harsh (high salt and acid or base concentrations) conditions. Here we report, a permeable graphene membrane operating in harsh conditions with no observable degradation. A permeate of pH neutral water with a flux of 25 ± 1 L m−2 h−1 is produced by this membrane through near (99.9 ± 0.1%) ion rejection from 0.6 M sodium chloride at pH 1 and pH 13, over 144 h. More complex ion solutions, including real acid mine drainage waste-water, were also successfully purified. These findings may present a membrane that is suitable to improve water supply and reduce the environmental impact of industrial waste-water.

Application of powdered steel slag for more sustainable removal of metals from impaired waters

Using abundant and cheap steel slag for metals removal from water represents an opportunity to recover waste material from one industry as a resource for another. In this study, powdered steel slag which contains lime (CaO) leftover from the steelmaking process, was evaluated and benchmarked against the relatively expensive and energy-intensive chemical sodium hydroxide (NaOH) for the removal of cadmium (Cd), manganese (Mn), and zinc (Zn) from two different mine drainage waters. Unlike isotherm and kinetic studies that represent most previous work, this study evaluated metals removal under realistic simulated water treatment conditions (doses, mixing, contact times, etc.), bringing the material one-step closer to actual full-scale implementation. In the neutral pH water with lower metals concentrations, approximately four times more steel slag (400 mg/L) compared to NaOH (100 mg/L) was required to achieve >70% metals removal. In the acidic pH water with higher metals concentrations, steel slag was insufficient to raise the pH at reasonable doses (<1,000 mg/L) but was shown to reduce NaOH dosing requirements by 25% (600 to 450 mg/L) when used in combination with steel slag (600 mg/L). Like NaOH, steel slag addition facilitated metal precipitate formation but also provided relatively high specific surface area (7.6 m2/g) for metal adsorption, particularly for Mn, a promising finding for future work to evaluate sludge recycle. Water treated with steel slag was also found to be more amenable to 0.45 μm filtration than water treated with NaOH.

Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

AbstractWe report a supramolecular strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. We utilized cobalt tetraphenylporphyrin (Co‐TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, as a building block to assemble the permanently porous supramolecular cage Co‐PB‐1(6) bearing six Co‐TPP subunits connected through twenty‐four imine bonds. Reduction of these imine linkers to amines yields the more flexible cage Co‐rPB‐1(6). Both Co‐PB‐1(6) and Co‐rPB‐1(6) cages produce 90–100 % H2O2 from electrochemical ORR catalysis in neutral pH water, whereas the Co‐TPP monomer gives a 50 % mixture of H2O2 and H2O. Bimolecular pathways have been implicated in facilitating H2O formation, therefore, we attribute this high H2O2 selectivity to site isolation of the discrete molecular units in each supramolecule. The ability to control reaction selectivity in supramolecular structures beyond traditional host–guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications.

Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide.

We report a supramolecular strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2 O2 . We utilized cobalt tetraphenylporphyrin (Co-TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, as a building block to assemble the permanently porous supramolecular cage Co-PB-1(6) bearing six Co-TPP subunits connected through twenty-four imine bonds. Reduction of these imine linkers to amines yields the more flexible cage Co-rPB-1(6). Both Co-PB-1(6) and Co-rPB-1(6) cages produce 90-100 % H2 O2 from electrochemical ORR catalysis in neutral pH water, whereas the Co-TPP monomer gives a 50 % mixture of H2 O2 and H2 O. Bimolecular pathways have been implicated in facilitating H2 O formation, therefore, we attribute this high H2 O2 selectivity to site isolation of the discrete molecular units in each supramolecule. The ability to control reaction selectivity in supramolecular structures beyond traditional host-guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications.

Aluminium Induced DNA-damage and Oxidative Stress in Cultures of the Marine Sponge Hymeniacidon perlevis

Aluminium is the most abundant element in the earth crust, and has no known biological function. However, it is an established neurotoxicant in its trivalent oxidation state, with exposure resulting in neurodegenerative diseases like Parkinson’s disease and presenile dementia. Although, the potential genotoxic and carcinogenic effects of aluminium are established in mammalian and other model system, there is however very limited information on aluminium genotoxicity in aquatic invertebrates. Mechanism of aluminium toxicity is also largely unclear. With a concentration range between 0.001– 0.05mg/L in near neutral pH water, and up to 0.5-1mg/L in an acidic water , aluminium poses a potential threat to the marine ecosystem, however it is poorly studied. This study, therefore presents for the first time, aluminium-induced DNA damage using the comet assay and reactive oxygen Species (ROS) formation using 2’, 7’-dichlorodihydrofluorescein diacetate (H2DCF-DA) assay as biomarkers of genotoxicity and oxidative stress in the inter-tidal marine sponge Hymeniacidon perlevis, respectively. H. perlevis is widely distributed in the British Isles, Mediterranean and the Arctic sea and has been reported as a model for environmental biomonitoring in aquatic ecosystem and as a suitable alternative to bivalves. In this study, cryopreserved single sponge cells of H. perlevis were cultured as viable aggregates and were thereafter treated with 0.1, 0.2, 0.3 and 0.4mg/L aluminium chloride (AlCl3) for 12 hours. Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Our results showed that non-cytotoxic concentrations of AlCl3 caused a statistically significant concentration-dependent increase in the level of DNA-strand break and reactive oxygen species formation single sponge cells of H. perlevis. There was also a statistically significant positive linear correlation between aluminium-induced DNA strand break and ROS formation suggesting the involvement of ROS in the causative mechanism of the aluminium induced DNA-strand breaks observed.

Electronic modulation of cobalt phosphide nanosheet arrays via copper doping for highly efficient neutral-pH overall water splitting

We report here, an effective strategy to optimize the electronic structure of CoP using copper doping, for greatly enhancing the intrinsic activity and conductivity of CoP in neutral-pH water splitting. As a result, the as-synthesized 3D self-supported Cu-doped CoP nanosheet arrays on carbon paper (Cu-CoP NAs/CP) exhibits admirable electrocatalytic performance toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with overpotentials of 81 and 411 mV at 10 mA cm−2 in 1.0 M PBS (Phosphate Buffer Solution), respectively. Moreover, a neutral electrolyzer, using Cu-CoP NAs/CP as both the anode and cathode, achieves a low cell voltage of 1.72 V at 10 mA cm−2, superior to that of the typical Pt/C||IrO2 couple (1.81 V) and of most of the state-of-the-art bifunctional electrocatalysts. Impressively, the electrolyzer can be driven by a single AA battery (∼1.5 V), indicating its practicality in neutral water or seawater splitting. Experimental and density functional theory (DFT) calculations results reveal that the incorporation of Cu into CoP can effectively improve the conductivity and optimize the electronic structure to facilitate the H* adsorption and desorption and the formation of O* intermediates (generated CoOOH active species), thus yielding superior HER and OER catalytic activities. This study opens up a promising way to rationally design highly efficient and low-cost electrocatalysts for electrocatalysis applications.

Hydrogen Production from Water Electrolysis Driven by High Membrane Voltage of Reverse Electrodialysis

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without CO2 emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of 1.1 × 10&lt;sup&gt;−4&lt;/sup&gt; mol cm&lt;sup&gt;−2&lt;/sup&gt; h&lt;sup&gt;−1&lt;/sup&gt; is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

Competitive interactions among H, Cu, and Zn ions moderate aqueous uptake of Cu and Zn by an aquatic insect

The absorption of aqueous copper (Cu) and zinc (Zn) by aquatic insects, a group widely used to assess water quality, is unresolved. This study examined interactions among Cu, Zn, and protons that potentially moderate Cu and Zn uptake by the acid-tolerant stonefly Zapada sp. Saturation uptake kinetics were imposed to identify competitive mechanisms. Decreasing pH reduced the maximum transport capacity, Jmax, in both metals, had little effect on the Cu dissociation constant, KD, and increased the Zn KD. Partial noncompetitive (Cu) and partial mixed competitive (Zn) inhibitor models most closely tracked the observed Cu and Zn influx rates across pH treatments. The estimated values for acid dissociation constants for the binary (proton-receptor) and ternary (proton-metal-receptor) complexes indicated the strong inhibitory effect of protons on Cu and Zn. In neutral pH water, Cu inhibited Zn influx, but Zn had little effect on Cu influx. The mechanism of Cu-Zn interaction was not identified. Results from separate Zn experiments suggested that the insect's developmental stage may affect the apparent Jmax. The study underscores some of the challenges of modeling metal bioaccumulation and informs future research directions.

Editors' Choice—A Monolithic Photoelectrochemical Device Evolving Hydrogen in Pure Water

We report the development of a fully-integrated, photoelectrochemical (PEC) device coupling water oxidation to hydrogen evolution using a III-V triple-junction photovoltaic (PV) embedded in a Nafion membrane. This architecture is genuinely monolithic, with wireless catalyst integration being achieved via compression of metal sputter-coated carbon electrodes against the front and back PV contacts. The resulting MEA-type, sandwich structure minimizes the path length for proton conduction through the membrane ionomer, while simultaneously preventing PV light attenuation by the catalyst layer, a common issue for monolithic PEC structures. Simulated, solar illumination of this construct, when operating in neutral-pH water, yields a peak solar-to-hydrogen efficiency of 12.6% during a four-day trial. While the wireless nature of monolithic PEC devices typically prevents the measurement of current flow and faradaic efficiencies, we circumvent this complication through the placement of an electrical shunt between the PV and the cathode catalyst layer, rerouting charge generated at the PV through a potentiostat prior to cathodic proton reduction. Using this configuration, we also show evidence of a corrosion current competing with anodic oxygen evolution under acidic conditions, highlighting the importance of quantifying product generation in monolithic devices.

Neutral-pH overall water splitting catalyzed efficiently by a hollow and porous structured ternary nickel sulfoselenide electrocatalyst

A hollow and porous structured nickel sulfoselenide catalyst was developed as a new type of bifunctional electrocatalyst for neutral-pH water splitting.

A Janus Nickel Cobalt Phosphide Catalyst for High-Efficiency Neutral-pH Water Splitting.

Transition-metal phosphides have stimulated great interest as catalysts to drive the hydrogen evolution reaction (HER), but their use as bifunctional catalytic electrodes that enable efficient neutral-pH water splitting has rarely been achieved. Herein, we report the synthesis of ternary Ni0.1 Co0.9 P porous nanosheets onto conductive carbon fiber paper that can efficiently and robustly catalyze both the HER and water oxidation in 1 m phosphate buffer (PBS; pH 7) electrolyte under ambient conditions. A water electrolysis cell comprising the Ni0.1 Co0.9 P electrodes demonstrates remarkable activity and stability for the electrochemical splitting of neutral-pH water. We attribute this performance to the new ternary Ni0.1 Co0.9 P structure with porous surfaces and favorable electronic states resulting from the synergistic interplay between nickel and cobalt. Ternary metal phosphides hold promise as efficient and low-cost catalysts for neutral-pH water splitting devices.

Hydrogen generation by the hydrolysis of mechanochemically activated aluminum-tin-indium composites in pure water

This paper presents results of our continuing project on the mechanochemical activation of Al-based composites for hydrogen generation [1,2]. A series of bi- and ternary Al, Sn, and/or In composites were mechanochemically prepared and their reactivities towards neutral pH water at ambient conditions determined. Hydrogen generation was compared to previously reported data from related studies in Refs. [1] and [2]. Scanning electron microscopy (SEM) energy dispersive x-ray spectrometer (EDS) analysis suggests that Sn and In could be distributed relatively homogeneously onto and into Al particles exteriors and interiors, respectively. Such distribution allowed continuous micro-galvanic activity between anodic Al and cathodic Sn and In during hydrolysis reactions. X-ray diffraction indicated that in-situ Sn–In intermetallic phase formation was determined by the Sn:In mol ratio of each composite. The formed Sn–In phases included Sn4In and SnIn3. Some AlSn phases were detected in ternary composites. Reactive composites (>95% yield) exhibited relatively similar reactivities and it was found that composites containing various intermetallic phases had shorter induction periods than composites containing a single intermetallic phase.

Monolayer CS as a metal-free photocatalyst with high carrier mobility and tunable band structure: a first-principles study

Producing hydrogen fuel using suitable photocatalysts from water splitting is a feasible method to harvest solar energy. A desired photocatalyst is expected to have suitable band gap, moderate band edge position, and high carrier mobility. By employing first-principles calculations, we explore a α-CS monolayer as a metal-free efficient photocatalyst. The α-CS monolayer shows good energetic, dynamic, and thermal stabilities and is insoluble in water, suggesting its experimental practicability. Monolayer and bilayer α-CS present not only appropriate band gaps for visible and ultraviolet light absorption but also moderate band alignments with water redox potentials in pH neutral water. Remarkably, the α-CS monolayer exhibits high (up to 8453.19 cm2 V−1s−1 for hole) and anisotropic carrier mobility, which is favorable to the migration and separation of photogenerated carriers. In addition, monolayer α-CS experiences an interesting semiconductor-metal transition by applying uniaxial strain and external electric field. Moreover, α-CS under certain strain and electric field is still dynamically stable with the absence of imaginary frequencies. Furthermore, we demonstrate that the graphite (0 0 1) surface is a potential substrate for the α-CS growth with the intrinsic properties of α-CS maintaining. Therefore, our results could pave the way for the application of α-CS as a promising photocatalyst.

Effective silicon nanowire arrays/WO3 core/shell photoelectrode for neutral pH water splitting

We report the first demonstration of a high-efficiency photoelectrochemical (PEC) water splitting reaction using a novel Si NWs/WO3 core/shell photoanode prepared by a mild and inexpensive metal-catalyzed electroless etching process followed by dip-coating, airing and annealing methods. The dense and vertically aligned Si NWs/WO3 core/shell nanostructure were characterized by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. In comparison to planar n-Si, Si NWs and planar Si/WO3, the Si NWs/WO3 samples showed significantly enhanced photocurrent over the entire potential sweep range. More significantly, the Si NWs/WO3 samples have an exceptionally low photocurrent onset potential of −0.6393 V versus reversible hydrogen electrode (RHE), indicating very efficient charge separation and charge transportation processes. The as-prepared electrode also has a photocurrent density of 2.7 mA cm−2 at 0.6107 V versus RHE in 0.5 M Na2SO4 solution under simulated solar light irradiation (100 mW cm−2 from 300 W Xenon lamp coupled with an AM 1.5 G filter). An optimal solar-to-hydrogen efficiency of about 1.9% was achieved at 0.2676 V versus RHE. Electrochemical impedance spectroscopy was conducted to investigate the properties of the charge transfer process, and the results indicated that the enhanced PEC performance may due to the increased charge separation. The x-ray photoelectron spectroscopy measurements indicated the chemical composition of the Si NWs/WO3 nanostructure. Our work has provided an efficient strategy to improve the energy conversion efficiency and photocurrent of water splitting materials.

Hydrogen generation of mechanochemically activated Al[sbnd]Bi[sbnd]In composites

The individual and combined effects of Bi and In on the morphology change and reactivity towards hydrogen release of Al during mechanochemical preparation of binary and ternary Al composites were determined. Subsequently, successfully prepared reactive composites were hydrolyzed with neutral pH waters under ambient conditions with the purpose of hydrogen generation. Reactive ternary composites were analyzed by scanning electron microscopy and X-ray diffraction. Results showed that phases found in the AlBiIn composites were Al, BiIn, BiIn3, and Bi3In5. In some cases Bi and In that did not partake in intermetallic BiIn phase formation were also found. The intermetallic phases between Bi and In were identified and characterized. It was concluded that the reactivity of ternary composites towards hydrogen yield were governed by the in situ formed intermetallic phases, and the remaining Bi and In that did not undergo intermetallic phase formation.