Simultaneous production of electricity and hydrogen from methanol solution with a new electrochemical technology

It is known that the reaction from methanol to hydrogen has a positive Gibbs free energy and therefore cannot occur spontaneously. In the present work, by utilizing the chemical energy of neutralization, a new electrochemical technology was developed to produce hydrogen and electricity from methanol solution simultaneously, without needing external energy input. In our designed electrochemical cell, hydrogen can be produced on cathode while methanol can be oxidized on anode with additional electricity production. The effect of anode surface area on hydrogen production rate and power output was also investigated. With anode apparent surface area of 6.15 cm², initial hydrogen production rate can reach up to 1.07 m³ H₂ m⁻³ d⁻¹ and the maximum power density output of 1.26 W m⁻² can be achieved, at the same time. Although it is only a preliminary work, our work is supposed to provide a new approach for the on-board hydrogen production for the application of various fuel cell technologies, which is urgently needed nowadays.     

Biological hydrogen production via dark fermentation: A holistic approach from lab-scale to pilot-scale

Biohydrogen is considered as fuel of future owing to its distinctive attribute for clean energy generation, waste management and high energy content. Suitable feedstock play important role for achieving high rate hydrogen production via dark fermentation process. In this regard, different organic wastes such as cane molasses, distillery effluent and starchy wastewater were examined as potential substrates for biohydrogen production by Enterobacter cloacae IIT-BT 08. Groundnut deoiled cake (GDOC) was considered as additional nutritional supplement to enhance biohydrogen yields. The maximum hydrogen yield of 12.2 mol H₂ kg⁻¹ COD_removed was obtained using cane molasses and GDOC as co-substrates. To further ensure reliability of the process, bench (50 L) and pilot scale (10000 L) bioreactors were customized and operated. The pilot scale study achieved 76.2 m³ hydrogen with a COD removal and energy conversion efficiency of 18.1 kg m⁻³ and 37.9%, respectively. This study provides an extensive strategy in moving from lab to pilot scale biohydrogen production thereby, providing further opportunity for commercial exploitation.     

Performance optimization of microbial electrolysis cell (MEC) for palm oil mill effluent (POME) wastewater treatment and sustainable Bio-H2 production using response surface methodology (RSM)

Microbial electrolysis cells (MECs) are a new bio-electrochemical method for converting organic matter to hydrogen gas (H₂). Palm oil mill effluent (POME) is hazardous wastewater that is mostly formed during the crude oil extraction process in the palm oil industry. In the present study, POME was used in the MEC system for hydrogen generation as a feasible treatment technology. To enhance biohydrogen generation from POME in the MEC, an empirical model was generated using response surface methodology (RSM). A central composite design (CCD) was utilized to perform twenty experimental runs of MEC given three important variables, namely incubation temperature, initial pH, and influent dilution rate. Experimental results from CCD showed that an average value of 1.16 m³ H₂/m³ d for maximum hydrogen production rate (HPR) was produced. A second-order polynomial model was adjusted to the experimental results from CCD. The regression model showed that the quadratic term of all variables tested had a highly significant effect (P < 0.01) on maximum HPR as a defined response. The analysis of the empirical model revealed that the optimal conditions for maximum HPR were incubation temperature, initial pH, and influent dilution rate of 30.23 ^°C, 6.63, and 50.71%, respectively. Generated regression model predicted a maximum HPR of 1.1659 m³ H₂/m³ d could be generated under optimum conditions. Confirmation experimentation was conducted in the optimal conditions determined. Experimental results of the validation test showed that a maximum HPR of 1.1747 m³ H₂/m³ d was produced.     

Powering microbial electrolysis cells by electricity generation from simulated waste heat of anaerobic digesters using thermoelectric generators

Waste heat from anaerobic digesters can be converted to electricity by using thermoelectric generators (TEG). Herein, such energy was employed to power a microbial electrolysis cell (MEC) for producing hydrogen gas. Four TEG units could deliver a voltage of ~0.5 V, sufficient to drive the MEC that achieved a hydrogen production rate of 0.48 ± 0.13 m³ m⁻³ d⁻¹. This rate was further improved to 0.75 ± 0.05 m³ m⁻³ d⁻¹ when the temperature difference for TEG was increased from 18 to 28 °C. There was no significant difference between the TEG-powered MEC and power supply-supported MEC (at 0.6 V), in terms of current generation, hydrogen production, and organic removal. Ambient air was also studied as a cold-side source for TEG, although some challenges were encountered to maintain a large temperature difference. Those results will encourage further exploration of using TEG as a feasible power supply for sustainable MEC operation.     

Hydrogen generation by alcohol reforming in a tandem cell consisting of a coupled fuel cell and electrolyser

The performance of a novel electro-reformer for the production of hydrogen by electro-reforming alcohols (methanol, ethanol and glycerol) without an external electrical energy input is described. This tandem cell consists of an alcohol fuel cell coupled directly to an alcohol reformer, negating the requirement for external electricity supply and thus reducing the cost of operation and installation. The tandem cell uses a polymer electrolyte membrane (PEM) based fuel cell and electrolyser. At 80 °C, hydrogen was generated from methanol, by the tandem PEM cell, at current densities above 200 mA cm⁻², without using an external electricity supply. At this condition the electro-reformer voltage was 0.32 V at an energy input (supplied by the fuel cell component) of 0.91 kWh/Nm³; i.e. less than 20% of the theoretical value for hydrogen generation by water electrolysis (4.7 kWh/Nm³) with zero electrical energy input from any external power source. The hydrogen generation rate was 6.2 × 10⁻⁴ mol (H₂) h⁻¹. The hydrogen production rate of the tandem cell with ethanol and glycerol was approximately an order of magnitude lower, than that with methanol.     

Ozonation aided mesophilic biohydrogen production from palm oil mill effluent

Ozone pretreatment of palm oil mill effluent (POME) was employed to improve sustrate biodegradability prior to biological H₂ production. The H₂ production was conducted at varing pHs from 4.0 to 6.0 to examine the impact of pH on the H₂ mesophilic production (37 °C). The optimal pH for H₂ production was 6.0 for both raw and ozonated POME. The POME concentrations were greatly influenced the yields and rates of H₂ production. At the optimal pH, the maximum H₂ production yield of 182 ± 7.2 mL.g⁻¹ COD (7.96 mmoL.g⁻¹ COD) was achieved at the ozonated POME concentration of 30,000 mg COD.L⁻¹. The maximum H₂ production rate (R_max) of 43.1 ± 2.5 mL.h⁻¹ was obtained at the ozonated POME concentration of 25,000 mg COD.L⁻¹. The highest total COD removal was 44% at of 15,000 mg COD.L⁻¹ ozonated POME. Acetic and butyric acids were dominant products during H₂ fermentation and tended to increase with the increased POME concentrations. Ozonation as a pretreatment process showed significant enhancement of the POME biodegradability , and subsequently improved the H₂ production H₂.     

Enhancement of bio-hydrogen generation by spirulina via an electrochemical photo-bioreactor (EPBR)

The biological production of hydrogen by microalgae is considered as an advantageous process. However, its yields are sometimes limited. To go beyond this limit, the improvement of the H₂ generation rate by Spirulina was studied via an electrochemical photo-bioreactor (EPBR). This EPBR led to hydrogen evolution rates of up to 27.49 and 13.37 mol of H₂.d⁻¹.m⁻³ for the anode and cathode chambers, respectively, under 0.3 V voltage and ~2.5 mA current. These results represent about a 4-fold increase compared to the H₂ production rate recorded without the application of a voltage. This increase in bio-hydrogen production is correlated with a drop in the concentration of NADPH. The Electrochemical Sequential Batch Reactor (ESRB) provided a more interesting total production rate which was 2.65 m³ m⁻³ d⁻¹, compared to the batch mode, which gave 1.2 m³ m⁻³.d⁻¹. The results show, for the first time, the boosting effect of the voltage on the metabolism of H₂ production by the Spirulina strain.     

Ruthenium supported on nitrogen-doped porous carbon for catalytic hydrogen generation from NH3BH3 hydrolysis

In this paper, ruthenium supported on nitrogen-doped porous carbon (Ru/NPC) catalyst is synthesized by a simple method of in situ reduction using ammonia borane (AB) as reducing agent. The composition and structure of Ru/NPC catalyst are systematically characterized. This catalyst can efficiently catalyze the hydrolysis of AB. The hydrogen production reaction is completed within about 90 s at a temperature of 298 K and the maximum rate of hydrogen production is 3276 ml·s⁻¹·g⁻¹ with a reduced activation energy of 24.95 kJ·mol⁻¹. The turnover frequency (TOF) for hydrogen production is about 813 mol_H2·mol_Ru⁻¹·min⁻¹. Moreover, this catalyst can be recycled with a well-maintained performance. After five cycles, the maximum rate of hydrogen generation is maintained at 2206 ml·s⁻¹·g⁻¹, corresponding to 67.3% of the initial catalytic activity. Our results suggest that Ru/NPC prepared by in situ reduction is a highly efficient catalyst for hydrolytic dehydrogenation of AB.     

A promising strontium and cobalt-free air electrode Pr1-xCaxFeO3-δ for solid oxide electrolysis cell

A promising strontium and cobalt-free ferrite Pr_1-xCa_xFeO_3-δ (PCF, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) has been synthesized successfully by glycine-nitrate combustion method and used as the air electrode of solid oxide electrolysis cell (SOEC) for steam electrolysis. The crystal structure and electricity conductivity of PCF are investigated in detail. According to the conductivity test, Pr_0.6Ca_0.4FeO_3-δ (PCF64) with higher conductivity is selected as the air electrode to preparing the single cell with structure of PCF64|GDC|SSZ|YSZ-NiO. Under SOFC mode, the maximum power density of the single cell is 462.93 mW cm⁻² at 800 °C with hydrogen as fuel. Under SOEC mode, the current density reaches 277.14 mA cm⁻² and the corresponding hydrogen production rates is 115.84 mL cm⁻² h⁻¹ at 800 °C at 1.3 V. In the 10 h short-term stability test, the cell shows good electrolysis stability.     

Hydrogen generation kinetics via hydrolysis of Mg2Ni and Mg2NiH4 powders

In this work, we produce Mg₂NiH₄ powder after hydrogenation of Mg₂Ni and employ them for hydrogen generation via hydrolysis reaction in different type of solutions. The analysis of Mg₂NiH₄ powder reveals surface changes after hydrogenation process which induces the occurrence of cracks and alterations of chemical bonds. The extremely intense hydrogen kinetics is observed using acidic solution, with hydrogen generation rate of approx. 600 ml g⁻¹·min⁻¹ in the first reaction minute. The activation energy for the hydrolysis of Mg₂NiH₄ is calculated to be 29.45 kJ mol⁻¹. An ageing experiment, which includes Mg₂NiH₄ powder stored for two months, discloses almost identical hydrogen generation volume as as-received Mg₂NiH₄ powder. Furthermore, the hydrolysis reaction between Mg₂NiH₄ and acidic solution is applied for electricity production via PEM fuel cell, which shows the maximum voltage generation of 1.28 V for more than 400 s with the external resistance of 200 Ω.     

Thermophilic hydrogen and methane production from sugarcane stillage in two-stage anaerobic fluidized bed reactors

This study evaluated the feasibility of H₂ and CH₄ production in two-stage thermophilic (55 °C) anaerobic digestion of sugarcane stillage (5,000 to 10,000 mg COD.L⁻¹) using an acidogenic anaerobic fluidized bed reactor (AFBR-A) with a hydraulic retention time (HRT) of 4 h and a methanogenic AFBR (AFBR-S) with HRTs of 24 h–10 h. To compare two-stage digestion with single-stage digestion, a third methanogenic reactor (AFBR-M) with a HRT of 24 h was fed with increasing stillage concentrations (5,000 to 10,000 mg COD.L⁻¹). The AFBR-M produced a methane content of 68.4 ± 7.2%, a maximum yield of 0.30 ± 0.04 L CH₄.g COD⁻¹, a production rate of 3.78 ± 0.40 L CH₄.day⁻¹.L⁻¹ and a COD removal of 73.2 ± 5.0% at an organic loading rate (OLR) of 7.5 kg COD.m⁻³.day⁻¹. In contrast, the two-stage AFBR-A system produced a hydrogen content of 23.9 ± 5.6%, a production rate of 1.30 ± 0.16 L H₂.day⁻¹.L⁻¹ and a yield of 0.34 ± 0.08 mmol H₂.g CODap⁻¹. Additionally, the decrease in the HRT from 18 h to 10 h in the AFBR-S favored a higher methane production, improving the maximum methane content (74.5 ± 6.0%), production rate (5.57 ± 0.38 L CH₄.day⁻¹.L⁻¹) and yield (0.26 ± 0.06 L CH₄.g COD⁻¹) at an OLR of 21.6 kg COD.m⁻³.day⁻¹ (HRT of 10 h) with a total COD removal of 70.1 ± 7.1%. Under the applied COD of 10,000 mg L⁻¹, the two-stage system showed a 52.8% higher energy yield than the single-stage anaerobic digestion system. These results show that, relative to a single-stage system, two-stage anaerobic digestion systems produce more hydrogen and methane while achieving similar treatment efficiencies.     

Bioelectricity recovery and pollution reduction of distillery wastewater in air-cathode SCMFC

Generation of electricity and treatment of the distillery wastewater (DW) were achieved in air-cathode single-chamber MFCs (SCMFCs). The maximum current density of 2.36 mA·m⁻² and power density of 39.21 mW·m⁻³ were obtained at DW concentration of 2000 mg COD.L⁻¹. The trends of current and power density were decreased with increasing concentration from 2000 to 4000 mg COD.L⁻¹. The maximum soluble COD removal was 62.2% (CE = 8.77%, 1500 mg COD.L⁻¹). The electrochemical activity of the microbes in the SCMFCs showed significantly high oxidized substrate in the semi-batch distillery wastewater operation. The microbial communities on the anode biofilms fed with a high concentration of distillery wastewater (4000 mg COD.L⁻¹) operation were analyzed based on 454 pyrosequencing of the 16S rRNA gene revealed different microbial communities. The dominant phylum were Proteobacteria (28.5%), Bacteroidetes (23.4%) and Chlorobi (22.8%), while Firmicutes (9.3%) were detected as a lesser proportion of the total community. The microbial community structures suggested that Proteobacteria might be important for the production of power density in distillery wastewater fed air-cathode SCMFC. These results demonstrate that the SCMFCs can simultaneously generate electricity and achieve wastewater treatment from a renewable source.     

Comparative study on bio-hydrogen production from corn stover: Photo-fermentation,dark-fermentation and dark-photo co-fermentation

In this study, three different fermentation methods, such as photo-fermentation (PF), dark-fermentation (DF) and dark-photo co-fermentation (DPCF) for bio-hydrogen production from corn stover were compared in terms of hydrogen production, substrate consumption, by-products formation and energy conversion efficiency. A modified Gompertz model was applied to perform the kinetic analysis of hydrogen production. The maximum cumulative hydrogen yield of 141.42 mL·(g TS)⁻¹ was achieved by PF, DF with the minimum cumulative hydrogen yield of 36.08 mL· (g TS)⁻¹ had the shortest lag time of 4.33 h, and DPCF had the maximum initial hydrogen production rate of 1.88 mL· (g TS)⁻¹·h⁻¹ and maximum initial hydrogen content of 44.40%. The results also indicated PF was an acid-consuming process with a low total VFAs concentration level of 2.90–4.19 g·L⁻¹, DF was a process of VFAs accumulation with a maximum total VFAs concentration of 12.66 g·L⁻¹, and DPCF was a synergistic process in which the total VFAs concentration was significantly reduced and the hydrogen production efficiency was effectively improved compared with DF. The energy conversion efficiency of PF, DF and DPCF were 10.12%, 2.58% and 6.45%, respectively.     

Hydrogen production from ammonia by the plasma membrane reactor

A new plasma membrane reactor (PMR) was developed to efficiently produce hydrogen from NH₃ with the use of atmospheric pressure plasma and a hydrogen separation membrane. The generation of high-purity hydrogen from NH₃ was also examined. First, hydrogen gas flowing into the PMR revealed the effect of the PMR on hydrogen separation. Hydrogen separation depends on the partial pressure of hydrogen gas supplied (P_{in, H2}) and permeated (P_{out, H2}) when P_{in, H2}^0.5 − P_{out, H2}^0.5 > 0. Second, NH₃ gas flowing into the PMR revealed its hydrogen production characteristics: the maximum hydrogen conversion rate of a typical plasma reactor (PR) is 13%, whereas the PMR converted 24.4%. Hydrogen obtained by hydrogen separation was approximately 100% pure. A hydrogen generation rate of 20 mL/min was stably obtained.     

Multi-electrode continuous flow microbial electrolysis cell for biogas production from acetate

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m²/m³). Under continuous flow conditions and a one day hydraulic retention time, the maximum current was 181 mA (1.18 A/m², cathode surface area; 74 A/m³) within three days of operation. The maximum hydrogen production (day 3) was 0.53 L/L-d, reaching an energy efficiency relative to electrical energy input of η_E = 144%. Current production remained relatively steady (days 3–18), but the gas composition dramatically shifted over time. By day 16, there was little H₂ gas recovered and methane production increased from 0.049 L/L-d (day 3) to 0.118 L/L-d. When considering the energy value of both hydrogen and methane, efficiency relative to electrical input remained above 100% until near the end of the experiment (day 17) when only methane gas was being produced. Our results show that MECs can be scaled up primarily based on cathode surface area, but that hydrogen can be completely consumed in a continuous flow system unless methanogens can be completely eliminated from the system.     

Techno-economic assessment of hydrogen production from seawater

Population growth and the expansion of industries have increased energy demand and the use of fossil fuels as an energy source, resulting in release of greenhouse gases (GHG) and increased air pollution. Countries are therefore looking for alternatives to fossil fuels for energy generation. Using hydrogen as an energy carrier is one of the most promising alternatives to replace fossil fuels in electricity generation. It is therefore essential to know how hydrogen is produced. Hydrogen can be produced by splitting the water molecules in an electrolyser, using the abondand water resources, which are covering around ? of the Earth's surface. Electrolysers, however, require high-quality water, with conductivity in the range of 0.1–1 μS/cm. In January 2018, there were 184 offshore oil and gas rigs in the North Sea which may be excellent sites for hydrogen production from seawater. The hydrogen production process reported in this paper is based on a proton exchange membrane (PEM) electrolyser with an input flow rate of 300 L/h. A financially optimal system for producing demineralized water from seawater, with conductivity in the range of 0.1–1 μS/cm as the input for electrolyser, by WAVE (Water Application Value Engine) design software was studied. The costs of producing hydrogen using the optimised system was calculated to be US$3.51/kg H₂. The best option for low-cost power generation, using renewable resources such as photovoltaic (PV) devices, wind turbines, as well as electricity from the grid was assessed, considering the location of the case considered. All calculations were based on assumption of existing cable from the grid to the offshore, meaning that the cost of cables and distribution infrastructure were not considered. Models were created using HOMER Pro (Hybrid Optimisation of Multiple Energy Resources) software to optimise the microgrids and the distributed energy resources, under the assumption of a nominal discount rate, inflation rate, project lifetime, and CO₂ tax in Norway. Eight different scenarios were examined using HOMER Pro, and the main findings being as follows:The cost of producing water with quality required by the electrolyser is low, compared with the cost of electricity for operation of the electrolyser, and therefore has little effect on the total cost of hydrogen production (less than 1%).The optimal solution was shown to be electricity from the grid, which has the lowest levelised cost of energy (LCOE) of the options considered. The hydrogen production cost using electricity from the grid was about US$ 5/kg H₂.Grid based electricity resulted in the lowest hydrogen production cost, even when costs for CO₂ emissions in Norway, that will start to apply in 2025 was considered, being approximately US$7.7/kg H₂.From economical point of view, wind energy was found to be a more economical than solar.     

Preparation and characterization of hydrogen storage medium (IMO/TPAC) and asymmetric supercapacitor (IMO/TPAC6TPAC) using imogolite (IMO) and biomass derived activated carbon from tangerine peel (TPAC) for renewable energy storage applications

The blooming of renewable energy technology is magnificent in order to overcome the shrinking availability of fossil fuels and global warming. Hydrogen is considered the most prominent clean and green energy carrier. Hence, the present work focuses on the preparation and characterization of imogolite (IMO) clay and highly porous-natured activated carbon derived from the Tangerine Peel (TPAC) nanocomposite. SEM exhibits the IMO/TPAC nanocomposite reveals the presence of IMO embedded at the surface of TPAC. From the BET studies, there is a profound enhancement for the specific surface area of IMO/TPAC nanocomposite (1323 m² g⁻¹) compared to pristine TPAC (902 m² g ⁻¹) and IMO (217 m² g ⁻¹). A 6.3 wt% hydrogen storage capacity was achieved at 70 °C and the same (6.3 wt%) amount of hydrogen desorption was noticed at 108 °C for the IMO/TPAC nanocomposite. The electrochemical hydrogen storage of the IMO/TPAC electrode exhibits a hydrogen discharge capacity of 2573 mAh/g at 41^st cycle with excellent columbic efficiency of 92.4%, capacitance retention of 86.2% and superior corrosion resistance of 20.3 mA/cm². The fabricated ASC exhibits a maximum specific capacitance of 183 F g⁻¹ and retains capacitance of 85.1% for 5000 cycles. The as-fabricated ASC has an excellent energy density of 125 Wh kg⁻¹ and power density of 2634 Wkg⁻¹ at a wide operating potential window of 2.1 V. This ASC could able to power blue and white LEDs. Hence, these excellent characteristics proved that the prepared nanocomposite may serve as an excellent energy storage material.     

Hydrogen production from alcohol wastewater with added fermentation residue by an anaerobic sequencing batch reactor (ASBR) under thermophilic operation

The objective of this study was to investigate the enhancement of hydrogen production from alcohol wastewater by adding fermentation residue using an anaerobic sequencing batch reactor (ASBR) under thermophillic operation (55 °C) and at a constant pH of 5.5. The digestibility of the added fermentation residue was also evaluated. For a first set of previous experiments, the ASBR system was operated to obtain an optimum COD loading rate of 50.6 kg/m³ d of alcohol wastewater without added fermentation residue and the produced gas contained 31% H₂ and 69% CO₂. In this experiment, the effect of added fermentation residue (100–1200 mg/l) on hydrogen production performance was investigated under a COD loading rate of 50.6 kg/m³ d of the alcohol wastewater. At a fermentation residue concentration of 1000 mg/l, the produced gas contained 40% H₂ and 60% CO₂ without methane and the system gave the highest hydrogen yield and specific hydrogen production rate of 128 ml/g COD removed and 2880 ml/l d, respectively. Under thermophilic operation with a high total COD loading rate (51.8 kg/m³ d) and a short HRT (21 h) at pH 5.5, the ASBR system could only break down cellulose (41.6%) and hemicellulose (21.8%), not decompose lignin.     

Methane production for sanitation improvement in Haiti

There is a great need for decentralized anaerobic digestion (AD) that utilizes wastewater for energy generation. The biochemical methane potential (BMP) of Haitian latrine waste was determined and compared to other waste streams, such as grey water, septage, and dairy manure. Average methane (CH₄) production for the latrine waste (13.6 ml ml⁻¹ substrate) was 23 times greater than septage (0.58 ml ml⁻¹ substrate), and 151 times greater than grey water (0.09 ml ml⁻¹ substrate), illustrating the larger potential when waste is source separated using the decentralized sanitation and reuse (DESAR) concept for more appropriate treatment of each waste stream. Using the BMP results, methane production based on various AD configurations was calculated, and compared with the full-scale field AD design. Methane potential from the BMP testing was calculated as 0.006–0.017 m³ person⁻¹ day⁻¹ using the lowest and highest latrine BMP results, which was similar to the values from the full-scale system (0.011 m³ person⁻¹ day⁻¹), illustrating the ability of BMPs to be used to predict biogas production from sanitation digesters in a smaller-scale setting.     

Efficient photocatalytic hydrogen production from formic acid on inexpensive and stable phosphide/Zn3In2S6 composite photocatalysts under mild conditions

Developing an efficient, stable and low-cost photocatalytic hydrogen production from formic acid is a daunting challenge and has attracted the intense interest of many of researchers. In this paper, we report the synthesis of novel composite photocatalysts (Ni₂P/Zn₃In₂S₆ (ZIS6) and MoP/ZIS6) and their catalytic performance for H₂ production reaction from formic acid under visible light irradiation, in which Ni₂P and MoP were used as cocatalysts to enhance hydrogen generation activity of ZIS6. The photocatalytic hydrogen production rates of the optimized 1.5 wt% Ni₂P/ZIS6 (45.73 μmol·h⁻¹) and 0.25 wt% MoP/ZIS6 (92.69 μmol·h⁻¹) were 3.5 times and 7.2 times higher than that of the pure ZIS6 (12.88 μmol·h⁻¹), respectively. The apparent quantum efficiency at wavelength λ = 400 ± 10 nm for the two photocatalysts was about 1.8% and 6.4%, respectively. Significantly, it was found that the remarkable improvement of hydrogen production performance is attributed to the introduction of the phosphide cocatalysts, which can serve as a charge separation center and an active site for photocatalytic hydrogen production from the decomposition of formic acid. The reaction mechanism of photocatalytic hydrogen production from formic acid was also proposed.